Overheating due to coolant loss

[southcoasting]

I have searched the threads and have some ideas on what to look for but posting this so that others and myself could go through some learning of my process.

First off, this has been really frustrating! I have a brand new engine rebuild do at a local machine shop. New head, new exhaust manifold, new pistons, rings, bearings, heat exchanger, etc.

Been through a whole mess of things for since launching my boat with this new engine. Most recently, I am struggling with milky oil and me putting constant antifreeze into the system. Obviously, the antifreeze is getting into the oil at this point. I now have to figure out how/why...��

I know the typical steps but let me share some of my symptoms:

1. Engine is hard to start. Takes a lot of cranking before running
2. Plugs look black if taken out
3. Runs great after turning on but I have to keep putting af into heat exchanger due to leak

Obvious next steps will have to be pressure tests.

Could be my water pump...but doubt it since I have the Oberdorfer with the weep hole...but it just seems like the leak is substantial...like I have to fill heat exchanger every 10 mins or it runs dry...

Going to boat today but super frustrated at this point...

[joe_db]

Yikes
Pressure test and compression test stat!
The best thing to find would be a head gasket needing replacement or maybe a hole in the manifold.

[capnward]

If your HX is draining in 10 minutes, that water has to be going somewhere, like into your crankcase. When it is running, check to see if your water pump is leaking out of the weep hole underneath the seals. I had mine leak so bad that it forced water into the crankcase through the accessory drive, as well as out the weep hole. The engine ran anyway, but overheated due to reduced coolant flow, as water was going other places besides the water jacket. The seals were shot. The bearings and shaft were replaced as well. If your local shop worked on the water pump, they may have installed the seals inside out, a common mistake. The engine being hard to start could be a different problem.

[Dave Neptune]

First, how much is the oil level going up? It should be about as much as you are adding coolant.
The first check I would do is a compression check to check the head-gasket. If the compression check does not show a low cylinder it will be time for a leak-down test of the manifold and block. First check the manifold as it is easy to isolate then the block.
Since you stated that all the plugs are black I would suspect the manifold as the culprit.

Dave Neptune

[Dave Neptune]

Part II

If it is the pump leaking there should be a bit in the bilge and the plugs would look no different than usual as the coolant would be dumped directly into the oil pan.
In your case I suspect a breech as in my post above since your plugs are compromised. That indicates the coolant going through the combustion cycle and not just leaking into the oil.

Dave Neptune

[joe_db]

If the engine was RWC you might see a different result,. It would not run out of coolant and overheat, it would just keep filling the crankcase.
*If* if is just a leaky pump, try re-plumbing to RWC with the non-leaky pump

[southcoasting]

First, how much is the oil level going up? It should be about as much as you are adding coolant.
The first check I would do is a compression check to check the head-gasket. If the compression check does not show a low cylinder it will be time for a leak-down test of the manifold and block. First check the manifold as it is easy to isolate then the block.
Since you stated that all the plugs are black I would suspect the manifold as the culprit.

Dave Neptune

Oil level went up a lot! See dipstick pic attached. Twice over the full level. I looked underneath water pump and don’t see a big enough leak to indicate it is that

Thanks for the heads up Dave. Yeah, I had read in one of the billetins that hard starting are causes for a leaky manifold...so attached is a pic of the number 1 plug. Also, how do I pressure test manifold? It is as easy as plugging up the exhaust section and pumping in from the intake of manifold? If so, I just did a few pumps and I could hear swirling inside towards block and no pressure being held...bad manifold then? Do I have this correct?

[southcoasting]

Posted pic of dipstick

[Dave Neptune]

First do a compression check!! f the compression is good it will be time to pressure check the manifold. The manifold is easy to check as all you need to do is plug one end of the water jacket and pressurize the other. Those points are where the coolant goes in and out of the manifold.

There are many links as to how to set up the manifold test with a "schrader valve", pressure gage and a bicycle pump.

Once the results of BOTH tests are negative then time to test the block.

Dave Neptune

[southcoasting]

First do a compression check!! f the compression is good it will be time to pressure check the manifold. The manifold is easy to check as all you need to do is plug one end of the water jacket and pressurize the other. Those points are where the coolant goes in and out of the manifold.

There are many links as to how to set up the manifold test with a "schrader valve", pressure gage and a bicycle pump.

Once the results of BOTH tests are negative then time to test the block.

Dave Neptune

Ok, but do I still need to if the manifold holds no pressure and I could hear air escaping back into exhaust?

[Dave Neptune]

With the amount of coolant you are losing I doubt it's the manifold as that liquid would have to get past the rings to get into the oil. I think the compression check will yield your problem due to the amount of loss.

The water passage is sealed inside the manifold and only gets in & out via the two fittings on the top.

Save time do a compression check first.

Dave Neptune

[joe_db]

WARNING - oil floats on water.
At first startup you are trying to lubricate the engine with pure water. After it runs a bit, you are trying to lubricate with oatmeal mush. Neither one works well.

[southcoasting]

Running compression test now...tons of water shooting up through plug holes...around 80 psi on all 4...cold engine

[southcoasting]

After replacing oring on pressure gauge, I got closer to 85-90 psi on 3 cylinders and 65 on cylinder 3

[Dave Neptune]

Did more moisture come out of #3?

Dave Neptune