H shaped Freeze crack, please help

[craze1cars]

Re: H shaped Freeze crack, please help

I have 2 pretty good size cracks on the sides of my 5.0L Volvo Penta GL also. Bought it that way super cheap last year from a pawn shop, expecting to put an engine in it over the winter. After compression testing and determining it seemed healthy inside and running strong, I JB Welded them up and took it out to the lake. That was about 25 to 30 engine hours ago...

It still runs like a top and oil is clean and perfect. Took my engine budget and added a tower and Perfectpass speed control instead! Now every time I go boating I just add one more thing to my checklist...inspect the JB weld patches for signs of failure. If or when they fail, I'll re-do them. I also stay on small inland lakes with plenty of traffic. I would NOT trust this thing on a long ocean trip...so there are safety issues to consider with hack repairs like this, depending on where you boat.

I simply got lucky. And you might too.

If it were me, BEFORE I did all this disassembly, I'd do a compression test. If it passes, I'd JB weld those suckers up and take it to the lake (with an oar at minimum...or better yet another buddy with a reliable boat and a tow rope...you might need it!)

Run the heck outta it for a while and THEN check the oil. If it's still looking normal, run the heck out of it some more and call it good.

If it fails any of these tests, start motor shopping.

It's about $6 experiment, with little to lose but some time and gas. Maybe you'll get lucky too...

That's what I'd do if it were me...and it WAS me...

 

[Maddness038]

Re: H shaped Freeze crack, please help

we have ran it on the water with the cracks in the engine (this was before we knew we had the cracks) and just recently we check the oil and its fine. i just took off the manifold on the left side so i could grind the crack and put jb wield on it. im going to put some pictures up after this post. i would also like ask how to do a compression test, i know it has to do with the pistons but im not sure what to do... and again thank you everyone for your help and input.

 

[nofuss]

Re: H shaped Freeze crack, please help

Firstly where i live if my engine block got a freeze crack i would have bigger problems than my boat

however being 18years old and working with your father to get your boat running I would recommend getting a junk yard block and doing the rebuild. It may cost you a bit more to do it right the first time, but there would be very little that could be compared with the experience that you would gain from doing a total engine rebuild.


When I was 17, I rebuilt my first engine, it was a 4 cylinder english car engine, and i dont remember but i dont think i would have known how to check for water in the oil then either. but i was a brave young boy who wanted a car. The experience I gained lead me to be a mechanic, on cars planes, boats, and even factory machinery, and now at 40 managing Oil drilling rigs.

If you think you can read and understand from books, buy a manual, pull your engine out, and see whats good, the sooner u do that better chance u have having good internals if there was any salt water getting into your engine.
If you are able to start the engine its generally an indication that your internals are generally good "now". this indicated that you can most likely just do a swap of the block and probably new manifolds. It may be wise to see if your dad has a friend who is a mechanic who could go with you to buy the engine block, as an experienced pair of eyes could better determine the condition. Usually a car block would have had less work than one from a truck, you may have a better chance of getting a "good" car block, but remember to reuse your marine camshaft (u will learn what that is in time) as the power the engine develops is dependent on this and cars need different ones than boats. actually trucks are closer but u already have a marine one. If you get an engine block from a sport car it may however have some benefits.

So I say bite the bullet, get a manual and do the rebuild. it would put you in an advantageous position, you would be the envy of a lot of your friends. as you would understand a lot more about engines than they would, be in a better position to fix the boat, your car or any other vehicle that may break down.

And you have one advantage that i did not have the Gurus here on iboats, and also the ones still learning like my self. who would help you out along the way. even if u ask a stupid question, and people laugh, you would learn, and be better for it in the end.
and you know who would end up with dad's boat with all the nice girls on it LOL LOL

Just my line of advice from my experience

P still No Fuss

 

[ftl900]

Re: H shaped Freeze crack, please help

A compression test is about the easiest thing you can do. I rented a tester from AutoZone and did mine in about half an hour.

Basically, you're removing ONE spark plug, threading in the compression tester, and then cranking the engine for a few seconds. I unplugged my coil so it wouldn't start. Then you write down which cylinder it is, and what the highest reading is. Then you unscrew the tester, put the plug back in and the plug wire back on, and move on to the next spark plug.

When you're done, you'll have a list of all cylinders and their compression. One or several cylinders that are unusually low in pressure indicates a cracked or warped head, cracked block, blown head gasket, or valve problem. The low numbers will indicate which bank or which cylinders have problems, and how severe the problem really is.

 

[Maddness038]

Re: H shaped Freeze crack, please help

nofuss, thank you for your thoughts and if the jb wield plan dosent work out thats the path we are going to take. now when im drilling the ends of the cracks so they dont go further how deep should i drill? I also closely inspected the exaust manifolds and they were not cracked and the freeze plugs were intact so thats a big relief. tomorrow we are going to grind the crack and degrease it with some carb cleaner (i heard that works well) and then maybe start puting the JB on the right side.

 

[bruceb58]

Re: H shaped Freeze crack, please help

A compression test is about the easiest thing you can do.

A compression test basically only tells you if the crack is in the cylinder area and may not even tell you that because if you have low compression it could be because of other things other than a crack. There are way more other places than the cylinders that the water jacket can crack and let water in the oil.

 

[Maddness038]

Re: H shaped Freeze crack, please help

thank you and we are going to do a compression test

 

[Silvertip]

Re: H shaped Freeze crack, please help

5.7 liter (350 cubic inch) GM 4-bolt main bearing truck blocks are getting more and more scarce in our neck of the woods. Dirt track racers gobble them up. Keep in mind whatever you find may need rebuilding as well as installation of all the marine stuff from your current engine. You learned a very hard lesson. Water freezes at 32 degrees. Expanding water breaks things including engine blocks. It takes so little time to drain a marine engine that I can't imagine skipping this important process.

 

[craze1cars]

Re: H shaped Freeze crack, please help

5.7 liter (350 cubic inch) GM 4-bolt main bearing truck blocks are getting more and more scarce in our neck of the woods. Dirt track racers gobble them up.

This is very true. And I'd like to add that the Cash for Clunkers mess took a MASSIVE and permanent bite out of 5.7L inventory.

The era of quick and relatively inexpensive junkyard engine replacements for all these boats is gradually coming to an end...

 

[jtmarten]

Re: H shaped Freeze crack, please help

If the internal water jacket(s) are cracked, most likely a compression test will tell you nothing. The valley wall is weaker than the cylinder wall, so no cracks/water into the cylinder, no loss of compression there.
Back it into the lake, keep it on the trailer and run it 'til shes at op temp for a while. Shut her down and check the oil. Clean & clear, you're good to go with external repairs. Milkshake, you're replacing at least the block.

 

[cr2k]

Re: H shaped Freeze crack, please help

It easier to remove all the spark plugs and easier on the starter, plus you want to block the carburetor open (full throttle) to allow all the air in you can. A compression test done under vacuum is not going to be as accurate.

Crank the engine over for at least 6 strokes.

Compression readings should be within 10% of each other.

Compression tester form Sears or Kragen is usually around $25-$30. Do Not Use the ones you just hold in. Get the screw in kind.

With no water in the oil you appear to have dodged a bullet!

To the guy who doesn't change the core plugs...So you are telling me where you run the water wont rust steel? The steel plugs will rust from the inside out and you will not know until they blow.

 

[bruceb58]

Re: H shaped Freeze crack, please help

He needs to do a pressure test of his cooling system...not a compression test! If the compression test comes back good he very easily can have a crack internally elsewhere!

 

[craze1cars]

Re: H shaped Freeze crack, please help

He needs to do a pressure test of his cooling system...not a compression test! If the compression test comes back good he very easily can have a crack internally elsewhere!

I don't think anyone is disagreeing. But it would be helpful to explain to this 18 year old poster exacly how to economically pressure test his open water cooling system at home while he has big H-shaped cracks in his block, so he knows what he should do in order to get this done.

Seems to me this might be semi-difficult to accomplish, but maybe not. Please give him a step-by-step, or point him to a link with one.

My thinking is this: Compression test will answer whether or not his motor will run for a while. And this can be done now...BEFORE even bothering with a JB weld patch. If it doesn't pass, throw the motor away now. But if it passes compression, he can then patch up the big holes for test #2...which certainly CAN be a pressure test (if he knew how to do it), OR could be a semi-extended on-water test-drive followed by pulling the dipstick and looking for an overfill and/or milkshake.

I see 2 ways to skin the same cat here...especially for someone who maybe doesn't know how, or doesn't have the tools handy, to pressure-test the cooling system on a boat in their driveway.

 

[jtmarten]

Re: H shaped Freeze crack, please help

To the guy who doesn't change the core plugs...So you are telling me where you run the water wont rust steel? The steel plugs will rust from the inside out and you will not know until they blow.

Never said they wouldn't rust, I ran her 6yrs with steel plugs and never had an issue. Most years from the end of April thru mid-Oct, 5-6 times out each month, and usually 3-4 more times from mid-Oct thru Dec, just had to drain and pull hoses after each time out later in the year (freezes come early @ 7300ft!)

 

[Gary H NC]

Re: H shaped Freeze crack, please help

I have seen JB Weld patches that have lasted for years.
If the area is prepped good and the block drained it will stick.
Acetone the area after the sanding or grinding.Do not grind or drill too deep in the block.
2 to 3 coats of JB is best because it will sag before it hardens.

For a few bucks and some labor it is worth a try.

 

[bruceb58]

Re: H shaped Freeze crack, please help

I don't think anyone is disagreeing. But it would be helpful to explain to this 18 year old poster exacly how to economically pressure test his open water cooling system at home while he has big H-shaped cracks in his block, so he knows what he should do in order to get this done.

Seems to me this might be semi-difficult to accomplish, but maybe not. Please give him a step-by-step, or point him to a link with one.

My thinking is this: Compression test will answer whether or not his motor will run for a while. And this can be done now...BEFORE even bothering with a JB weld patch. If it doesn't pass, throw the motor away now. But if it passes compression, he can then patch up the big holes for test #2...which certainly CAN be a pressure test (if he knew how to do it), OR could be a semi-extended on-water test-drive followed by pulling the dipstick and looking for an overfill and/or milkshake.

I see 2 ways to skin the same cat here...especially for someone who maybe doesn't know how, or doesn't have the tools handy, to pressure-test the cooling system on a boat in their driveway.

He can't pressure test the block until he does his JB weld fix if he so decides to do it. As far as testing the pressure in the cooling, he can take the two hoses that go to the manifolds and tie them together. Easiest way to apply pressure is to get a fitting that tests pressure in gas lines and adapt some pipe pieces so it can be put into the water intake hose to the thermostat.

The compression test is fine for seeing if his engine is ok but it has nothing to do with the block crack problem.

 

[Maddness038]

Re: H shaped Freeze crack, please help

okay. if i do a pressure test on the cracks it would fail it, like i said the cracks gush water. here is what I'm going to do. first before i fix anything im going to do a compression test i googled how to do one and my friend has a tester. i want to do this to make sure that the heads are intact and fine. next im going to grind off the paint around the cracks and then degrease that area. im going to pound the area that bulged out back down, and then im going to patch it with the JB Wield. now i need to know how/what i need to have to do a pressure test. after that im going to launch the boat on the lake and run it for a while. im then going to check the oil, and see if it has turned into the milky liquid, im going to go from there and keep you guys posted. Again i want to thank every one for their time and knowledge.

 

[jtmarten]

Re: H shaped Freeze crack, please help

Sounds like a good plan. I wouldn't get too far from the dock, prob best to test still attached to the trailer. If one or both side ruptured, you could fill the bilge with water quickly.

 

[craze1cars]

Re: H shaped Freeze crack, please help

im going to pound the area that bulged out back down, and then im going to patch it with the JB Wield.

I agree with your plan with one mild exception. I will encourage you to exercise a little caution here, with pounding it back down. That bent cast metal is VERY, VERY brittle. If you pound it back down in an effort to flatten it, it COULD snap completely off...which would turn your current cracks into very large, gaping holes. These are harder to fill.

You can probably get by with hammering gently in on the parts that are bent out and see if they will start to work their way back down into better alignment with each other, but check frequently and often as it bends back for any new cracks or stress marks forming...as soon as you see anything questionable STOP, no matter how far out of position the metal still is.

It's preferable to glob the JB weld on thicker (via multiple thin coats), and end up with an external bulge in that location, than to be forced into dealing with a large hole to fill...

I sincerely hope you are as lucky as I was, and that you are able to run this motor for several more years into the future...

 

[bruceb58]

Re: H shaped Freeze crack, please help

Personally, I would get a different block.