Cracked Block - or - Blown Head Gasket

[Coors]

Re: Cracked Block - or - Blown Head Gasket

Welcome to used boats.
You now have a full-time hobby/ job...

 

[rndcomp]

Re: Cracked Block - or - Blown Head Gasket

Yeah, my wife is already starting to feel a little jealous. Oh well, she will get over it once I get the boat back on the water.

 

[Meauran]

Re: Cracked Block - or - Blown Head Gasket

Pull the cooling manifold and pull all your plugs. With the coil wire off the distributor crank the engine and check your compression. Use ONLY a screw in tester .......

I couldn't have a more similar predicament. Basically, I did the same thing so I have been reading along hoping to pick up on the solution here.

I think I need to rule out a warped head or damaged block. It seems the best way to do this is the compression test.

Bob, you say to pull the cooling manifold and check the compression. Are these two different steps or do you need to pull the cooling manifold in order to check the compression?

Thanks. Sometime my reading comprehension is a little weak...

 

[rndcomp]

Re: Cracked Block - or - Blown Head Gasket

Meauran - I am planning to do my compression test this evening. I will post the results as soon as I know them. Just so that you know, I am not planning to pull the coolant manifold (aka Heat Exchange?) when I do the test. I don't see how it would make a difference. I may pull the heat exchange out and do a pressure test though.

This brings up another question. How do I check for a bad heat exchange? Can I just put pressure on the cooling system and look for coolant coming out. Or, do I need to have someone else do a pressure test?

Thanks!

 

[bjcsc]

Re: Cracked Block - or - Blown Head Gasket

Meauran - I am planning to do my compression test this evening. I will post the results as soon as I know them. Just so that you know, I am not planning to pull the coolant manifold (aka Heat Exchange?) when I do the test. I don't see how it would make a difference. I may pull the heat exchange out and do a pressure test though.

This brings up another question. How do I check for a bad heat exchange? Can I just put pressure on the cooling system and look for coolant coming out. Or, do I need to have someone else do a pressure test?

Thanks!

Meauran: The cooling manifold has no effect on the compression test. I think Bob suggested it for rndcomp because 1) It was in the way of removing the plug and 2) He suspects it may be the problem and he may as well avoid more water getting into the cylinders while cranking and running the test.

The most common cause of water ingestion is riser failure. Next would be a quick shut down at high rpm and dieseling. Basically you want to

1) Remove plugs and remove as much water as you can.
2) Restart it to remove remaining water
If the water doesn't come back - great. If it does, repeat step 1 and then
3) Check condition of risers/manifold and the gasket between the two
4) Check compression - leak down test if necessary
5) Pressure test cooling system (and/or exchanger)

rndcomp: You'll have to pressure test your exchanger unless you can see obvious damage. Figure out how to plug the antifreeze path and get 15 psi or so of air into it. Your problem is water in the engine so running it and looking for it won't work (it will be leaking on the inside)...

 

[rndcomp]

Re: Cracked Block - or - Blown Head Gasket

OK - Here is more information on my problem....

I did my compression test tonight (it was run cold, I did not warm the engine up first) and the numbers were 125,130,125,125. I think that these are good numbers. In addition I was albe to remedy my sparking battery by replacing the cables and connectors. There was no water in any cylinders (at least none came out during the compression test). Is this good news... I am hoping so. I started the engine and it sounded good except for the whining noise described below.

The new issue that I have is that when the engine is running, I hear a whinning/hissing noise, which I believe is coming from the alternator. My guess is that the belt is not aligned properly. Is there a secret to aligning the belt that I don't know.

Either way, is my next step to pressure test the cooling system to see why I am overheating? Since the compression test did not reveal any bad news (I hope not at least) should I take her out on the water and watch the temperature gauge.

I need some more help here, but I do appreciate everyone's involvement to date.

Thanks!

 

[Coors]

Re: Cracked Block - or - Blown Head Gasket

Take a straight edge ( board, level, piece of metal) and place it exactly over the lops of the crank pulley. If it doesn't hit all the other pulleys comepletly in line; there is your problem- start looking at, putting washers behind brackets(or bend them) to align them.

 

[bjcsc]

Re: Cracked Block - or - Blown Head Gasket

OK, now you're getting somewhere. Those numbers are great. You've ruled out your headgasket and valvetrain. The whining noise is interesting. It would be especially interesting if it turned out to be your circulating pump instead of your alternator thus explaining your overheating issue.

Just to recap, you had a bad "front cam seal" that caused a problem and that has been fixed, but it still overheated, correct? You're making progress...keep it up...

 

[Coors]

Re: Cracked Block - or - Blown Head Gasket

Hmmm, time for a stick, or a piece of metal to place in the suspected areas.
and find the noise.

 

[rndcomp]

Re: Cracked Block - or - Blown Head Gasket

Take a straight edge ( board, level, piece of metal) and place it exactly over the lops of the crank pulley. If it doesn't hit all the other pulleys comepletly in line; there is your problem- start looking at, putting washers behind brackets(or bend them) to align them.

I only have one belt on my sytem, and that is from the main rotor to the alternator. I think the right solution may be to play with the washers and get it o align better. Thanks for the advice!

 

[rndcomp]

Re: Cracked Block - or - Blown Head Gasket

OK, now you're getting somewhere. Those numbers are great. You've ruled out your headgasket and valvetrain. The whining noise is interesting. It would be especially interesting if it turned out to be your circulating pump instead of your alternator thus explaining your overheating issue.

Just to recap, you had a bad "front cam seal" that caused a problem and that has been fixed, but it still overheated, correct? You're making progress...keep it up...

Sort of. The problem was that I seriously overheated the engine last time I was out. When I returned home and checked the coolant and the oil, both appeared to be empty. So I filled the system with fresh oit, and I then assumed that I had water in my oil (which turns out not to be the case, it must have been some of the older oil mixing with the fresh oil to give it a darker look). As for the front cam seals, when the engine runs, I can see water leaking out (a steady drip) from the front starboard side of the engine (right behind the alternator) so I assumed that I have a bad front cam seal. The real question is what caused me to lose all (or a majority of) my coolant which is most likely why it overheated in the first place? Could a leaking cam seal cause a severe loss of coolant? What else could it be? I plan to hook the whole system up again and do a pressure test on the coolant system and look for leaks. I am guessing that since the thermostat is not going to be open that I will not be able to check for a leak at the cam seal. Also, I assume that I can not check the heat exchanger without pulling it off.

I hope that this provides more details to everyone.

Thanks so much! It sound like there may be hope for this engine (and for me)

 

[bjcsc]

Re: Cracked Block - or - Blown Head Gasket

As for the front cam seals, when the engine runs, I can see water leaking out (a steady drip) from the front starboard side of the engine (right behind the alternator) so I assumed that I have a bad front cam seal. The real question is what caused me to lose all (or a majority of) my coolant which is most likely why it overheated in the first place? Could a leaking cam seal cause a severe loss of coolant?

Yes. Those engines have an aluminum impeller on the end of the camshaft that serves as the circulating pump. The outer seal keeps the coolant in the cooling system and the inner seal keeps it out of your oil. It's designed to drip when the outer seal fails in order to let you know to service it before the inner seal fails and lets coolant into the engine.

Here's a link describing how it works (and how to fix it)...

 

[Meauran]

Re: Cracked Block - or - Blown Head Gasket

So that's it? Once the compression is checked, he can be confident that he didn't warp a head or crack the block?

rndcomp, please clarify here, are you STILL having an overheating issue or did you only have the one incident that you have traced to a lack of coolant due to the failed cam seal? My experience is that absolutely yes, a leaking cam seal can drain all of the coolant and overheat the engine. In my case, I found all of the missing coolant sitting in the bilge.

I've mentioned that I did the same thing to the same engine last weekend and am working my way through the problem now. It overheated once and then after it cooled, I refilled the coolant just so that I could get the boat from my dock to the ramp. It ran fine on the way to the ramp, except for the leaking coolant which I just kept topped off for the short trip.

I'll be checking my compression over the weekend, anyway to attempt to rule out severe engine damage.

 

[andy1canada]

Re: Cracked Block - or - Blown Head Gasket

Howdy from Canada.

Rnd...

Check out my last post (reply to) on this engine...

'1986 Mercruiser 170 4 cylinder'
Packers4ever

... it's been bumped about 4 pages ahead of this one (look in June 27th time frame).

Don't give up on this little powerhouse just yet.

Sage advise from Bob although I would contend that the '470' is not at all in the same league as the '3.0-L' Merc (considerably more HP/torque) and I don't believe they shared the same final drive ratio.

Hope this helps.

Cheers,
Terry

 

[rndcomp]

Re: Cracked Block - or - Blown Head Gasket

At this point I am not sure if I still have the overheating issue. I am hoping to do a pressure test tonight, just to check everything out on the FWC system. My biggest concern was that I had done some serious damage to the engine by overheating it. It appears that I have gotten VERY lucky.

Is it OK for me to take the boat out and watch the temp very closely (while also monitoring coolant level) and see how she behaves? What are the concerns with this? If the only problems that I have are a bad water pump and a possible bad impeller in the stern drive that I will get them fixed. Otherwise, if I was looking at some serious troubles (cracked block, etc...) I would most likley scrap the boat.

To all of the experts out there: What do you recommend? What is the most likely scenario? If I do the pressure test, what should I be looking for?

One more interesting note, I was told when I purshased the boat that the cam shaft was just replaced. If so, wouldn't it be logical that the cam seals were also replaced? Could I have a cracked hose that is leaking in the same location as the weep vent that is leading me to believe that the seal is bad.

I know.... I know.... so many questions, but this is the first time that I have dealt with a boat before.

thanks to all!