Confusing Volvo 4.3 GL overheat issue

[stockdad]

Engine Serial #: 4012069403
'02 Volvo Penta 4.3GL

3 weeks ago, on the 3rd trip of the season. Engine overheats and I have to get towed to shore of the mighty Columbia.

Checked impeller....toast. Replaced it.

Also blew a hole in the verticle exhaust bellow. Replaced it.

Checked oil, a tad dark but not too bad. Replaced it.

Ran engine for 10 minutes (driveway with muffs). No problems/no overheat.

Checked oil again, looks great.

Ran engine for another 10 minutes. No problems/no overheat.

FOLLOWING WEEKEND

Tried to start in driveway with muffs before hitting the water. Won't start.

Advice from father who was still concerned with the head gasket....pull the spark plugs and see if water comes out. So I did, one by one. No water.

One of the spark plugs broke off at the ceramic portion. Got new plugs.

Pulled the broken plug....water came out.

I did NOT do ANYTHING to the engine between the first time I pulled the plug and the second time....besides pull other plugs. Did one of the other plugs release some vacuum that was previously holding the water in?

Where did the water come from? If it was water from the river, I don't believe the boat would have ran for almost 20 minutes. Also, wouldn't the oil have been looking like a frappacino? If it was the head gasket, wouldn't there be water in the oil AND been some smoke of some kind AND some overheating issue? None of which are the case.

Ideas?

 

[Dakota47]

Re: Confusing Volvo 4.3 GL overheat issue

spray some oil in the cylinders quick before it locks up..

 

[stockdad]

Re: Confusing Volvo 4.3 GL overheat issue

And then?

I can do that....but what about the cause of the problem?

 

[Limited-Time]

Re: Confusing Volvo 4.3 GL overheat issue

And then?

I can do that....but what about the cause of the problem?

Compression test would be my next step. And as for water in the oil from a head gasket, not necessarily. Depends on where the gasket is compromised at.

 

[flabum]

Re: Confusing Volvo 4.3 GL overheat issue

There are a few things that could have got damaged in the overheat. You overheated it enough to melt a hose, so other damage is almost a certainty.
1) Exhaust manifold could be cracked
2) Riser could be cracked
3) Riser to manifold gasket could be burned through
4) Cylinder haed can be warped
5) Cylinder head gasketcould be blown
6) Block could be cracked

First thing is to drain the exhaust manifolds and block, pull all the plugs, spin the motor over to expell as much water as you can. Spray CRC or WD40 in the wet cylinders and continue to spin the motor over. Next, do a compression test. If you get two cylinders side by side that are low, you got a warped head and blown gasket. If you got one cylinder low, you got just a blown gasket. If compression is good all around (within 5 - 10 PSI on 6 revolutions each), then start looking at the risers and manifolds.

 

[mikeneal]

Re: Confusing Volvo 4.3 GL overheat issue

Could be a blown riser gasket. I overheated a SBC Volvo Penta couple years ago and a riser gasket failed and I hydrolocked it. I got water out, WD40 and did all the above listed things and I got lucky.

 

[stockdad]

Re: Confusing Volvo 4.3 GL overheat issue

Update.....

Went to do a compression test, but the battery was dead. Battery charging tonight and will complete compression test tomorrow.

However, we did a cylinder leakage test on the cylinder 3 (which had the water) and cylinder 1.

Cylinder 3 hit 30% (70% sealed)
Cylinder 1 hit 10% (90% sealed)

40% (60% sealed) and under is consider low and acceptable.

If this does end up being a problem that I need to trace through the exhaust manifold and risers....how do you discern where the problem lies?

 

[rodbolt]

Re: Confusing Volvo 4.3 GL overheat issue

ditch the compression test, stick with the leakdown.
15% leakage is maximum allowable, anymore and you gotta go find why that cylinder cant seal.
with air applied to the suspect cylinder open the throttles fully, air escapeing the intake means an intake valve, air escaping the exhaust means exhaust valve, if its freshwater cooled remove the heatexchanger cap before testing and look for bubbles in the tank when testing, remove the hoses going to the bottom of the manifolds, listen for air coming from a hose air coming from the hose will mean a leak into the cooling system seawater system.
I always prefer leakdown testing over compression testing, especially on 2 strokes.
leakdown testing not only gives an accurate indication of a cylinders actual sealing capeability it can aide in pinpointing what part of the sealing failed.
on large opening a plastic bag and some rubber bands will aide in finding air, it will try to blow up like a ballon if air is escaping a hose.

 

[stockdad]

Re: Confusing Volvo 4.3 GL overheat issue

Update to leakdown test.

Throttle wide open / exhaust pipe removed / this engine is raw-water cooled, so no heat-exchanger / hoses removed from bottom of manifolds.

Cylinder 1 - 1% leakage
Cylinder 3 - 28% leakage - seems to be intake leakage and possibly some exhaust.
Cylinder 5 - 20% leakage - seems to be intake leakage and possibly some exhaust.

Cylinder 2 - 32% leakage - we are thinking this may possibly be a bad reading, because we cannot find where it is leaking. It sounds like it is leaking from the gauge, but if that were the case it would have that sound before hooked up to the block....does that description make sense? But we cannot find the outsource of the leakage.
Cylinder 4 - 8% leakage
Cylinder 6 - 10% leakage

One of my good friends is helping me with this and he knows his way around an engine, as he owns his own mechanic shop. He is curious on your standard of 15% leakage or lower. With non-marine engines, 40% and lower is acceptable.....is there something about marine-engines that make the tolerances different?

Thanks again!

 

[cyril420]

Re: Confusing Volvo 4.3 GL overheat issue

15 percent is a good standard. It sounds to me like you have burnt or tuliped valves

 

[stockdad]

Re: Confusing Volvo 4.3 GL overheat issue

Well, I decided to tear into it a bit....starting with the exhaust.

Exactly as mikeneal suspected the riser gasket was shot. The exhaust manifold gasket was completely fine.

Riser gasket
http://i70.photobucket.com/albums/i101/xxdbkxx/Boat Problems/IMAGE_081.jpg

Exhaust manifold gasket
http://i70.photobucket.com/albums/i101/xxdbkxx/Boat Problems/IMAGE_079.jpg

Replaced both gaskets and gave it a test run in the driveway with muffs.

You could tell there was a slight misfire, so we stopped the engine and checked the plugs. We found that cylinder 2 was black and fouled. We cleaned it up and tried it again with the same result.

Test the wires, they seemed fine.

Just out of curiosity, we switched the wires from 1 and 2 (yes, we switched them on the distributor cap as well.) The engine ran smoother, still seemed to be a slight misfire.....but all plugs were fine. Weird.

Took it out on the water yesterday for about an hour drive. Slight misfire still apparent, but ran decently and stayed very cool. Didn't have a chance to inspect the plugs or anything when we got home, but will do that today/tomorrow.