Mercruiser 260 rebuilt - Water in cylinders and oil?

[Overkill82k5]

Re: Mercruiser 260 rebuilt - Water in cylinders and oil?

Try the Mercruiser maintenance manual, works wonders.

I did reference the manual...

I put the heads back on this morning and also the intake. I did seal the head bolts this time even though they werent the problem originally. I loosened all the rockers to keep the valves from opening so I could pressurize the cooling system and see it the intake manifold, oil pan, and/or cylinders would collect water.

With the exhaust manifolds loose (cold) and the system pressurized I have water running out of the #2 exhaust port. I dont seem to be getting any water in the oil pan anymore or in any of the cylinders. At first glance it appears as though I have a head cracked in the water jacket. It is probably the one that originally had the exploded valve in it, and the crack probably caused the hot valve to go boom.... I guess thats good news and not-so-good news all at the same time...

I am still going to keep checking with longer term tests to make sure thats the only problem. I have a gut feeling that at least one more is going to rear it's ugly head within the day, but we will see... Keep your fingers crossed for me...

 

[Overkill82k5]

Re: Mercruiser 260 rebuilt - Water in cylinders and oil?

While standing there exorcising the milkshake demons from my motor, I remembered I had a set or two of heads sitting on a shelf somewhere. I found 2 sets of heads that I think are from 4 bolt main truck motors.

One set are 14014416's with 1.53" intake and 1.84" exhaust valves in it. These are the cleanest looking ones.

The other set are 333882's with 1.51" intake and 1.94" exhaust valves in it. These look good, just lots of caked/baked on oil.

The cracked heads currently on the motor are 462624's.

Now, which set to cleanup and use?

I will pull the heads back off the motor and compare the valves to the others and hopefully I can do a straight swap. I have the tools to swap the valves, but it's virgin territory for me. Maybe I will go all out and get/put new seals in em since I have them unattaached to a motor... I guess when it rains, it pours... haha. I do love learning though...

Anyone have any advice or insight? Gut says tear down the heads and reseal em...

 

[HT32BSX115]

Re: Mercruiser 260 rebuilt - Water in cylinders and oil?

Once you select the heads you're going to use, it might not be a bad idea to just take them to a machine shop and have them touch up the seats, check and/or machine for "flat" and check them for cracks etc.......

 

[Overkill82k5]

Re: Mercruiser 260 rebuilt - Water in cylinders and oil?

I was entertaining that idea but didn't want to spend the extra money. Thinking about it now though, it would probably be cheaper in the long run to have them gone through professionally. Just the gaskets and a couple oi/filter changes to clear out the water will put me about even with what it would cost to have them done...

Great advice, thanks.

 

[Overkill82k5]

Re: Mercruiser 260 rebuilt - Water in cylinders and oil?

Update: Well I got the suspect heads pulled off, pulled the valves out of them and found that a couple of the exhaust passages were rotted through. That definitely explains were the water was coming from (hopefully the only palce)...

I chose the set of 14014416's to be the replacements. The heads have been decked down so compression will jump a bit. I had concerns of detonation being a problem so I decided to polish the chambers and also cleaned up the intake and exhaust runners. I pulled the old intake valves out of the junk heads since they were 1.94's and replaced the 1.84's in the new heads. The seats all looked great and I opened the valve openings up a tiny bit by just smoothing the casting texture. This turned into a much bigger project than originally anticipated, but hopefully the extra time and attention to detail will prove worthwhile.

I also pulled the seals out of the junk heads to use on the new ones. The new ones only had the tiny square 0-ring type seal while the old ones had the much heavier umbrella type. I will also use the rockers, pushrods, and springs from the junk heads. They seem to be a bit heavier duty. The valve guides all looked great on the new set of heads also so when this is finally done and put back together I should have a sweet setup with a little extra kick in the pants...

 

[HT32BSX115]

Re: Mercruiser 260 rebuilt - Water in cylinders and oil?

Update: Well I got the suspect heads pulled off, pulled the valves out of them and found that a couple of the exhaust passages were rotted through. That definitely explains were the water was coming from (hopefully the only palce)...

I hate to be the "I told you so guy" (again ) but a machine shop would have found that problem before doing anything to them!

The seats all looked great and I opened the valve openings up a tiny bit by just smoothing the casting texture.

I do hope you're at least going to "lap" the valves. If you have any sealing problems in the valves, you may end up with burned valves.

Again, (if you don't have a valve & seat grinder) I wouldn't put ANY valves (even new ones) in an "off the shelf head" without at least checking for good valve-to-seat seal........

If you end up with higher compression, that might be VERY bad. If you experience a detonation "event" at a high power setting, you won't know it until you punch a hole in a piston.......

You might consider measuring the piston height and head combustion chamber volume so you can get a ball park number. you might need a thicker head gasket....

Maybe I am stating the obvious and you've already done all this stuff......


Just more stuff to consider.....


ymmv!


Rick

 

[Bondo]

Re: Mercruiser 260 rebuilt - Water in cylinders and oil?

I hate to be the "I told you so guy" (again ) but a machine shop would have found that problem before doing anything to them!


I do hope you're at least going to "lap" the valves. If you have any sealing problems in the valves, you may end up with burned valves.

Again, (if you don't have a valve & seat grinder) I wouldn't put ANY valves (even new ones) in an "off the shelf head" without at least checking for good valve-to-seat seal........

If you end up with higher compression, that might be VERY bad. If you experience a detonation "event" at a high power setting, you won't know it until you punch a hole in a piston.......

You might consider measuring the piston height and head combustion chamber volume so you can get a ball park number. you might need a thicker head gasket....

Maybe I am stating the obvious and you've already done all this stuff......


Just more stuff to consider.....


ymmv!


Rick

I pulled the old intake valves out of the junk heads since they were 1.94's and replaced the 1.84's in the new heads.

Ayuh,... 'n to go along with what Rick's sayin'....

Ya can't just go stuff Bigger valves in the heads, unless the Seats Match 'em...

 

[Flysfloatsor]

Re: Mercruiser 260 rebuilt - Water in cylinders and oil?

Did we address the thread sealer issue with the head bolts? That is, after you get new heads...

You have to put thread sealer on all the head bolts with an SBC.

This is a good opportunity though, if you have the coin, to get a nice set of heads.

 

[Overkill82k5]

Re: Mercruiser 260 rebuilt - Water in cylinders and oil?

I planned to put the 1.94's in, but after pricing having the heads worked to fit the new valves I decided to stick with the original 1.84's. So, no worries there. Thanks for the "heads up" on the valves .

Since the machine shop supposedly checked out the rotted heads, I won't be taking anything back there... They've caused me to learn all kinds of new things, which isn't necessarily bad in the long run.

I haven't re-sealed the head bolts yet since I just used the old gaskets to run it on the test stand and the bolts still had the sealant "plug" stuck to em. If I can run it without more water getting into the oil I will then tear it back down to put new head and intake gaskets in and clean/reseal the bolts, before buttoning it up for install in the boat. They should still be sealed well.

I spent all day going through the new (actually used, off of another motor I had previously) heads. Doing the valve work today was actually kinda fun. I polished up the chambers and cleaned out alot of carbon deposits and casting flashing. I have them back on the block almost ready for a test run in the morning. Torquing heads down is starting to feel way too familiar. I have to set the valves lash, re-install the exhaust manifolds and set base timing, then I should be test firing it again on clean oil. If the milkshake demons stay exorcised, I will have only one or two more days of tearing down/building up to go then she will be ready to be stuffed back where she belongs. I've been working on this motor in the garage for so long, the thought of actually putting it in a boat seem almost foreign.

When I tear it back down (post water intrusin repair/testing) I will cc the heads and measure the clearances to see where my compression is. The last thing I want is to have to run this thing on avgas and/or start replacing pistons. Thanks Rick, for the reminder. I am so excited yet exhausted with this emotional roller coaster. Being my first real rebuild, I expected as much though. Luckily for me I was recently laid off and now have all kinds of time on my hands, too bad I'm now short on money. It always seems to be one extreme or the other... haha.

Aight, I've rambled on enough. I will post an update after the next test run and hopefully be in better shape, motor-wise...

Thanks again for the advice. Sometimes it's too easy to get ahead of yourself and miss something important, causing another catastrophic even...

 

[HT32BSX115]

Re: Mercruiser 260 rebuilt - Water in cylinders and oil?

Well with gas prices going up I'll bet that Avgas isn't all that much more than boat-premium!! (it's anywhere from $5.15 to $5.70/gal here)


Good luck!


Rick

 

[Overkill82k5]

Re: Mercruiser 260 rebuilt - Water in cylinders and oil?

Well, the testing commenced today, now that the rain and storms passed. I got her all back together and test fired it. Good news, no more water leaking into the motor. The bad news is it runs like utter crap. It takes some throttle pumping to get it to fire and when it does it sputters bad at lower rpm's. It sounds mean when you get off idle, sort of like it's big cammed, but it's running bad rich with lots of unburned fuel (heavy gas/exhaust smell) and sounds rough down low. Also had a few backfires through the carb. I suspect my "head work" was not up to par (what? It was my first shot at it! haha), or I have some bad vacuum leaks. Vacuum leaks are likely since I didnt use a fresh intake gasket but it seems almost too rough for just vacuum leaks. I only ran it for 2-3 minutes on 93 octane, since I have no idea what the compression ratio is yet and I dont want to risk blowing out a piston.

Long story short(er), It's holding H2O and I can now begin to tear it back down, again, and do some checking up on the heads. I will cc the old ones and the new(er) ones and see where I am with compression. I may pull my other, undecked, set down and strap them on for kicks and giggles if I can find the motivation. I just dont know if I have it in me to start this process this weekend... I am feeling the burn from throwing around all this iron as of late...

Any more ideas/tips/tricks are still welcomed. It seems that I am still quite a ways from being "out of the woods" with this monster...

Wish me luck...

 

[RogersJetboat454]

Re: Mercruiser 260 rebuilt - Water in cylinders and oil?

Well, the testing commenced today, now that the rain and storms passed. I got her all back together and test fired it. Good news, no more water leaking into the motor. The bad news is it runs like utter crap. It takes some throttle pumping to get it to fire and when it does it sputters bad at lower rpm's. It sounds mean when you get off idle, sort of like it's big cammed, but it's running bad rich with lots of unburned fuel (heavy gas/exhaust smell) and sounds rough down low. Also had a few backfires through the carb. I suspect my "head work" was not up to par (what? It was my first shot at it! haha), or I have some bad vacuum leaks. Vacuum leaks are likely since I didnt use a fresh intake gasket but it seems almost too rough for just vacuum leaks. I only ran it for 2-3 minutes on 93 octane, since I have no idea what the compression ratio is yet and I dont want to risk blowing out a piston.

Long story short(er), It's holding H2O and I can now begin to tear it back down, again, and do some checking up on the heads. I will cc the old ones and the new(er) ones and see where I am with compression. I may pull my other, undecked, set down and strap them on for kicks and giggles if I can find the motivation. I just dont know if I have it in me to start this process this weekend... I am feeling the burn from throwing around all this iron as of late...

Any more ideas/tips/tricks are still welcomed. It seems that I am still quite a ways from being "out of the woods" with this monster...

Wish me luck...

Overkill,
The 14014416 casting # heads you have installed now are 305/5.0L heads (if you weren't aware), which originally would have started out with 58CC combustion chambers before they were milled. These heads bolted to a stock bore H.O. 305 were good for a 9.5:1 CR.

Now figure in the fact that you have a 350 block, which in it's stock bore would most likely have at least a 10:1 CR if not higher with these heads installed. Then figure in the fact that your block is bored to .040, and there was a good chance that Jasper probably decked it to make a nice clean surface for the head gaskets. All this info boils down to the fact that you now most likely have too much compression, especially for 1.84 intake valves and a stock cam to support, and that is probably why your engine is running like crap.

My suggestion to you is to focus your attention on the other pair of heads you have ( Casting #333882, which are 76CC 350/400 heads), or to track down another set of 70-76CC truck heads (ebay should be loaded with machined, ready to use examples) which would have the 1.94 valves you need, and would also give you a pump-gas friendly compression ratio too.

You can use this to look up casting#'s ; http://www.kendrick-auto.com/chevrolet_head_casting_number_re.htm

You could also consider upgrading the heads to Vortec 350 style heads which would give you a least a 30hp "kick in the pants". Of course you would need the associated intake manifold, rocker arms, etc to use the Vortec heads.

 

[Overkill82k5]

Re: Mercruiser 260 rebuilt - Water in cylinders and oil?

Overkill,
The 14014416 casting # heads you have installed now are 305/5.0L heads (if you weren't aware), which originally would have started out with 58CC combustion chambers before they were milled. These heads bolted to a stock bore H.O. 305 were good for a 9.5:1 CR.

Now figure in the fact that you have a 350 block, which in it's stock bore would most likely have at least a 10:1 CR if not higher with these heads installed. Then figure in the fact that your block is bored to .040, and there was a good chance that Jasper probably decked it to make a nice clean surface for the head gaskets. All this info boils down to the fact that you now most likely have too much compression, especially for 1.84 intake valves and a stock cam to support, and that is probably why your engine is running like crap.

My suggestion to you is to focus your attention on the other pair of heads you have ( Casting #333882, which are 76CC 350/400 heads), or to track down another set of 70-76CC truck heads (ebay should be loaded with machined, ready to use examples) which would have the 1.94 valves you need, and would also give you a pump-gas friendly compression ratio too.

You can use this to look up casting#'s ; http://www.kendrick-auto.com/chevrolet_head_casting_number_re.htm

You could also consider upgrading the heads to Vortec 350 style heads which would give you a least a 30hp "kick in the pants". Of course you would need the associated intake manifold, rocker arms, etc to use the Vortec heads.

Awesome information Roger! I am getting ready to tear it back down now that I know it holds water. Now I can concentrate on getting it running good again and putting it back together right and properly sealed.

I tried cc'ing the old heads and they appear to be 52 - 54 cc chambers (casting #462624's). On the high comp heads they have the number 167 stamped into the side of them by someone, like a machinist. I though maybe they were 167 cc but that's way too much for just the heads. Maybe they were 167cc total on the motor they came off of (probably a 305)? When I get em pulled off I will cc them to see what the difference is. I'm about to go check the 333882's chamber volume. They look bone stock so hopefully they will mellow it out a bit.

It's funny how you can "hear" the higher compression. When it does light off and spin up a bit it sounds mean as all get out, but you can tell it's not healthy. I should have the 333882's ready for install by tomorrow and have it together and running by tomorrow night. I had some plans get cancelled so now I can push straight through to get this rolling again. I'm starting to get excited again... lol.

Stay tuned...

 

[RogersJetboat454]

Re: Mercruiser 260 rebuilt - Water in cylinders and oil?

Awesome information Roger! I am getting ready to tear it back down now that I know it holds water. Now I can concentrate on getting it running good again and putting it back together right and properly sealed.

I tried cc'ing the old heads and they appear to be 52 - 54 cc chambers (casting #462624's). On the high comp heads they have the number 167 stamped into the side of them by someone, like a machinist. I though maybe they were 167 cc but that's way too much for just the heads. Maybe they were 167cc total on the motor they came off of (probably a 305)? When I get em pulled off I will cc them to see what the difference is. I'm about to go check the 333882's chamber volume. They look bone stock so hopefully they will mellow it out a bit.

It's funny how you can "hear" the higher compression. When it does light off and spin up a bit it sounds mean as all get out, but you can tell it's not healthy. I should have the 333882's ready for install by tomorrow and have it together and running by tomorrow night. I had some plans get cancelled so now I can push straight through to get this rolling again. I'm starting to get excited again... lol.

Stay tuned...

Original heads gotta be more than 54CC's, especially for something coming from Jasper as a 260hp marine replacement engine.

If you google search the 462624 casting # they come up as this;

462624.. 76-87.. 1.94/1.50" or 2.02/1.60".. 76 CC Chambers

Most postings at the various web sites that google hits on also have at least 1 person saying these heads crack easily too.

The 167 is meaningless. Either Jasper, GM, or some other un-known entity in the life of that head stamped it on there. Everyone measures combustion chamber volume on a cylinder-by-cylinder basis. Nobody I know of totals them up, and if that were the case with your heads, 167/ 4 = 41.75cc's each, your engine would have a compression ratio in the teen's.

Don't know what you have for pistons in there right now, but if they are flat tops, you want to stay in the 70CC neighborhood which should keep your CR somewhere in the pump gas friendly 9:1 area.

Dust off the other set of heads you have and try them out, they should be fairly close to what you pulled off there. Just keep in mind their at least 30 years old, they were the first generation of light weight smog heads (prone to cracks/ not great performance), and if they haven't ever been gone through by a machine shop then they probably need to be freshened up.

 

[Overkill82k5]

Re: Mercruiser 260 rebuilt - Water in cylinders and oil?

I easily could have mis-counted when I was adding up the chamber volume on the old heads. 54 does seem way low. Since I didnt plan on using them anymore due to leaking I just did a quick cc and was distracted.

I do have flat top pistons in the block now. The 30 overs that came out were domes. The guy I got the boat from said it was a really fast boat. For a 23 foot Sea Ray weekender, fast doesnt seem like it should be in the description, but if the old motor was high compression it could have been a monster (until it blew up). With cutting to 40 over I was glad the pistons I had were flats. I dont want to have to run high test, but still may end up having to stick to 89 octane or so.

I am resistant to spending the money for a shop to go through the heads. I plan on cleaning them up and putting new seals in em and checking the valve guides. I will also lap the valves. The seats look really good on these, just a little oily residue which should clean up pretty easily. Since these are also prone to cracking, I wont be investing any money in them. I have time, but am short of $$. I will keep my eye out for another set of heads that are not prone to cracking. Maybe I can find a set do swap on before I actually get it in the boat. I dont want to have to pull the engine back out in a few months for more head problems. Any idea on what casting numbers to keep a look out for? I may have to buy a whole truck (junker) to get what I need, but I enjoy scrapping, so that is feasible.

Any thoughts on polishing the combustion chambers? Wouldn't this slightly lower the CR and help with detonation resistance? That was my goal with the 305 heads, but I would have to do more than polish to get the CR in line. I thought they were 350 heads when I started on them but didnt look up the numbers. I suppose it was a great way to get some experience before doing the set that counts. haha.

Ok, I'm off to the garage to start tearing the heads off and cleaning up the next set to try.

Thanks again for the info!

 

[RogersJetboat454]

Re: Mercruiser 260 rebuilt - Water in cylinders and oil?

I easily could have mis-counted when I was adding up the chamber volume on the old heads. 54 does seem way low. Since I didnt plan on using them anymore due to leaking I just did a quick cc and was distracted.

I do have flat top pistons in the block now. The 30 overs that came out were domes. The guy I got the boat from said it was a really fast boat. For a 23 foot Sea Ray weekender, fast doesnt seem like it should be in the description, but if the old motor was high compression it could have been a monster (until it blew up). With cutting to 40 over I was glad the pistons I had were flats. I dont want to have to run high test, but still may end up having to stick to 89 octane or so.

I am resistant to spending the money for a shop to go through the heads. I plan on cleaning them up and putting new seals in em and checking the valve guides. I will also lap the valves. The seats look really good on these, just a little oily residue which should clean up pretty easily. Since these are also prone to cracking, I wont be investing any money in them. I have time, but am short of $$. I will keep my eye out for another set of heads that are not prone to cracking. Maybe I can find a set do swap on before I actually get it in the boat. I dont want to have to pull the engine back out in a few months for more head problems. Any idea on what casting numbers to keep a look out for? I may have to buy a whole truck (junker) to get what I need, but I enjoy scrapping, so that is feasible.

Any thoughts on polishing the combustion chambers? Wouldn't this slightly lower the CR and help with detonation resistance? That was my goal with the 305 heads, but I would have to do more than polish to get the CR in line. I thought they were 350 heads when I started on them but didnt look up the numbers. I suppose it was a great way to get some experience before doing the set that counts. haha.

Ok, I'm off to the garage to start tearing the heads off and cleaning up the next set to try.

Thanks again for the info!

Can't give you any great tips on the best old school style GM iron heads. Personally the only GM iron head I focus on now is the vortec's. I believe GM's current production old school style (casting # 3998993) "hecho in Mexico" heads that they use on the 290hp crate engine are decent heads for what they are. They are 75CC truck heads that should be fairly happy running 89 octane in your engine. There was a heavy version of this casting # used in the early 70's. Those may not be too bad either, but at this point are 40 years old. I would recommend doing a google search for "GM 76cc heads" and do a little reading about the pro's an con's at the different sites. www.NastyZ28.com seems to come up allot when I have been doing the searches for info.

Polishing the combustion chambers won't make a huge difference on the CR, you would have to be overly aggressive to see much of a change. Personally I would just leave the the combustion chambers alone, but If you still want to do something, I would just use the K.I.S.S. method. Make sure you don't have any casting flash, and very gently round any sharp edges. You're not building a fuel motor here. You shouldn't have much issue with detonation, especially In the 9:1 CR range that you would be in, plus the fact you are running a limitless supply of cool water for coolant.

I wouldn't have been surprised if you were tickling the 11:1 Compression ratio range with the 305 heads. Some people usta use 305 heads as a poor mans way to bump their compression up. With enough massaging on the right castings, bigger valves, and a long duration cam they flow OK. But now there are so many other better, and cheap choices for heads that make good power, most people don't bother with them.

Keep us posted...

 

[Overkill82k5]

Re: Mercruiser 260 rebuilt - Water in cylinders and oil?

Wheeew... Finally got the 3rd set of heads finished and almost ready to be slapped on... What a PITA... I am seriously hoping that this will be my last head refresh for, at least, a couple of weeks. The first two sets were easy compared to this set. They were gunked up pretty bad and needed alot of attention. The intake valves were gunked up with what looked like burnt rubber. Kinda like what you get on your fenders when you do a standing burnout. It didnt want to come off the intake tract very easily. The valves were easy to clean compared to the runners. It looked like whoever had these heads before me ran the engine of stuff straight out of the La Brea tar pits! On the bright side, I have developed techniques that will make the next set much easier...

That's all I have for an update today. Tomorrow should bring the re-assembly and test firing (again). I found my digital cam and am thinking about video-ing the first start for posterity, and you're enjoyment. We'll see how motivated I am after putting this thing back together for the 4th time. haha.

Will post up more when I have more to post...

 

[Overkill82k5]

Re: Mercruiser 260 rebuilt - Water in cylinders and oil?

The valves and seats were in rougher shape than anticipated. It took me almost 4 days to get the valve seats cleaned up and lapped. I spent most of today putting everything back together. I plan on adding that last few things in the morning and then doing the test run. Stay tuned...

 

[Bt Doctur]

Re: Mercruiser 260 rebuilt - Water in cylinders and oil?

Or these

 

[Overkill82k5]

Re: Mercruiser 260 rebuilt - Water in cylinders and oil?

Finished putting everything back on the motor and got her ready to fire this morning. I was very relieved to hear it fire off after 20 seconds of cranking (had to prime the carb). Fired off nicely and idled well from the get go.

I have it purring along in the driveway running clean oil through it to clear out all the nasties that were in her from before. I have 10 gallons of premium that I plan to put through her, then change the oil again and get her ready to transplant.

Thanks to everyone for the help and advice. I'm still looking around for a set of vortec heads that I can afford to clean up and have ready to go when these crack or rot through, or I just feel like tinkering some more (maybe this winter). Hopefully these will at least get me through this boating season reliably. My intake manifold also had some decent rust in it (though not leaking... yet). I am also gonna keep an eye out for another intake to go with the heads. Anyone have any recommendations on intakes?

As a topic for another thread... I am considering changing this boat/motor over to a closed loop cooling system. I have alot of research to do yet, but from what I've found so far it seems to be a pretty expensive endeavor. If anyone has any tips, tricks or insight on that, I welcome that info too....

Bt Doctur: Those sound like a viable option for transplant. Would you recommend them as a good replacement?