overheating and puking out overflow

[crabmanjv]

I have recently bought a 1978 glasply with a 305 185hp omc 800. It has sat for many years but I have got it running smoothly on muffs. Problem is that the engine overheats before it gets to temp. (160) pukes coolant out of overflow @ about 120-130 degrees. Replaced thermostat but cant see any water movement thru heat exchanger ( not getting a chance since it overflows before it gets to temp). Suspect circulation pump (on engine) or plugged up heat exchanger, exhaust mans. Any tips to narrow or solve problem .. Thanks

 

[Don S]

Re: overheating and puking out overflow

I would suggest you take off the heat exchanger cap and top off the coolant. The do a cylinder leakdown test (basically just pressurize each cylinder while the valves are closed) and see if the coolant bubbles.

 

[crabmanjv]

Re: overheating and puking out overflow

Thanks for the feed back Don. I assume this is directing me towards a blown head gasket? I was considering trying to flush my cooling system (if possible) for starters hoping that there was just some blocking and then pulling my water pump (on engine) to see if it was rusted up or even functional. This boat has been sitting for about ten years and there has been flakey rust externally everywhere possible. The pressure test sounds easy enough but I do not have a compressor. Im thinking its not a head gasket since I see no water in oil? By the way I own some lots on kelp st. in OS. -wonderful place

JV

 

[Don S]

Re: overheating and puking out overflow

It could be a cracked head, cracked block, or a part of the head gasket that goes between the cylinder and a water port.
It would have nothing to do with water getting into the oil, and it probably wouldn't.
I don't see where flushing the system will do anything. That would cause it to overheat, your problem is surfacing well before it gets warm enough for it to overheat.
As far as the compressor, hey, it takes tools to troubleshoot and work on boats. No getting around it.

 

[Bondo]

Re: overheating and puking out overflow

Ayuh,........

If you don't have an Air Compressor,....
You probably don't have a Cooling System Pressure Tester either......
If you did,....
You could do the headgasket test, Backwards......
If you Pressurize the Cooling System,+ the pressure Drops,.....
You could look for the Loss of Coolant......

Btw,.........
I agree with Don,.....
Chances are it's Not a lack of circulation, as it occurs Before it comes Up to Temp...........

 

[crabmanjv]

Re: overheating and puking out overflow

Ok I will try a pressure test hopefully next weekend and if I get bubbling in my heat exchanger in each cylinder that will rule out a head gasket right? Is'nt that the same as doing a compression test? Forgive my stupidity this is the first V8 stern drive I have troubleshot. I still cant get the circulation pump out of my mind because it was froze up along with the crank when I got the boat. Does'nt a circ. pump move some water before the thermostat opens all the way up to (160)?

jv

 

[whywhyzed]

Re: overheating and puking out overflow

I recommend changing the w/p impeller in the outdrive.

 

[Bondo]

Re: overheating and puking out overflow

and if I get bubbling in my heat exchanger in each cylinder that will rule out a head gasket right?

Nope,........

If you get any Bubbling,..... That's the cylinder that the Headgasket is Gone in.......

 

[Robj]

Re: overheating and puking out overflow

If you cannot do a leakdown test or cooling system test, can you do a compression test? Do that to start and see what the numbers are. It may not tell the full story, but is a starting point.

Have a great day,

Rob.

 

[crabmanjv]

Re: overheating and puking out overflow

Thanks for the advice. I have a coolant pressure gauge in hand and a spare circ pump. I will do some testing before posting any replys.

jv

 

[crabmanjv]

Re: overheating and puking out overflow

I did the cooling system pressure test @ 15lb and it dropped down around 14 1/2 -14 3/4lb and stayed there for 3 hours. Seems normal since I have a very very slight seep out of my thermostat housing cover. I havent pulled the suspect circulation pump yet because the spare I had did not match. I hope the pressure test has ruled out head gasket and cracked block.

 

[Don S]

Re: overheating and puking out overflow

I hope the pressure test has ruled out head gasket and cracked block.

Not really, your compression in the cylinders is usually 130 psi or above. Well above your 15 psi, and pushing air, not liquid.
Bet you did your test with coolant in the system didn't you.

 

[crabmanjv]

Re: overheating and puking out overflow

Yes I did the pressure test with the coolant in did not consider to drain the system. I will drain sys tommorrow and before I rip out the circ pump I will try the test again. Maybe you could expain the difference. I'm leaning toward the pump since it and the crank were both froze. I think it is possible that the impeller was stripped from the pump shaft or it was so froze that the impeller might have broke or lost a blade. I think they are only brass or bronze. I will find out soon.

 

[Don S]

Re: overheating and puking out overflow

I'm leaning toward the pump since it and the crank were both froze.

Your problem is occuring BEFORE it gets warm. Even if the circ pump was still froze up, it wouldn't blow the coolant out till it got hot and started overheating. But your not getting that hot.
Crank Froze???? The engine is probably rusted up inside the cylinders and rings rusted together because of water.
If you want to throw a bunch of money at it since you don't seem to understand the system, or how it works go for it. But you will still have the problem.
You need to do a leakdown test to find what is leaking and where.

 

[SuperNova]

Re: overheating and puking out overflow

Actually, there is a quicker way to test the system for a compression leak into the cooling system.

attach your cooling system pressure tester like you normally would, but don't pump it up, and then fire up the engine. If there is a leak from compression, the needle will rise fairly fast. Just be ready to shut the engine off again so you don't hurt your pressure tester. If pressure doesn't rise at all or rises very slowly then you have passed the test.

While you have your tester there, why don't you pressure test the heat exchanger cap? If it is weak, it will vent off much sooner. 120*F creates plenty of pressure to pop a cap valve that is weak.
--
Stan

 

[crabmanjv]

Re: overheating and puking out overflow

First off thanks for the input. I have done most testing suggested except for Dons leakdown test. The only reason I havent done the leakdown test is I'm waiting on a compressor (I have the fitting in hand). I did a compression test and found 1,2,3,4,5,7 between 115-120 psi. 6 and 8 were around 110 and when i squirted some oil in 6,8 they went up to 120 ( beleive that told me compression was leaking around the rings and not through the head or gasket.. I tried the coolant pressure test with engine running and did not build any significant pressure quickly. I pressure tested the cap and found 2 out of three caps that would not hold pressure. Put new cap on now I'm able to run the engine up to temp 160 before I see some overflow (about 10 minutes). My upper portion of the heat exchanger is hot and do not see any circulation. There is a hose from the top part of the heat exchanger that runs to the port side exhaust manifold that wants to bulge like there could be blockage in the exhaust manifold. Thats when I shut it down. Should I be able to blow air through this hose?? I'm suspecting that my exhaust manifold could be plugged up not letting any water circulate. Also I disconnected the raw water intake from the bottom of the heat exchanger and it had good flow. I do not have any diagrams on the water flow through the heat exchanger and into the rest of the system (this would be a help). My next step I'm unsure of maybe cleaning out exhaust manifold??

thanks jv

 

[Don S]

Re: overheating and puking out overflow

Are you sure that "Overflow" isn't from the heat exchanger being to full?
If you fill it all the way up with no room for expansion, it's going to overflow, no matter what, till it gets to a certain level. Then it will be ok.

 

[crabmanjv]

Re: overheating and puking out overflow

I do not have any manual or history that covers the flow or service on the H.E. I did fill it up and possibly too much (about the same as I would a radiator) but it did not seem normal for the top portion of the H.E to be so bubbling hot. It also did not seem normal for the hose going from the H.E into the port side exhaust manifold to be bulging around the clamps. When I shut down it took a few minutes to relieve the pressure in the hose and for the coolant in the top part of the H.E to quit bubbling. All said the temp gauge did not go over 160. If I do not fill the H.E up what level would U suggest. I can see your point of expansion. With the fluid level low and the cap off as the engine heats up to temp should I be able to see circulation?

thanks jv

 

[Don S]

Re: overheating and puking out overflow

My question now is, was the water in the top of the heat exchanger actually HOT while it was bubbling, or just bubbling.
From the sounds of your original post, it was just "Puking water out the overflow" even when well below operating temp (120? to 130?).
You might check with your local NAPA (and possibly others), they have a kit to put some chemicals in the heat exchanger to check for combustion gases that could indicate a blown head gasket etc.

 

[crabmanjv]

Re: overheating and puking out overflow

Don S my coolant was hot. When I originally posted I was getting coolant puking out overflow @ around 120* +-. that was from a bad cap that lost pressure down to 5lbs. Now I have a new cap I'm able to run the engine up to 160* (about 10 min.) then it starts to overflow. It is not gushing out the overflow like it did with the old cap but it is still draining out and yes the coolant is hot. I would have let it run longer because the temp hasnt went over 160* but the gurgling and the bulging hose told me I should shut down. After shutting down and letting it cool enough to pull the cap off ,I fired back up to see if I could see any coolant moving in the HE. It ran for 30-40 secs or so and did not notice any movement then purged out the cap hole.

thanks jv