Exhaust in engine's raw-water circuit?

[Will Mauldin]

So the symptom is exhaust--or some other gas--finding its way into the raw-water circuit of my Universal 5411 diesel engine. What's the disease?
The mystery occurred as I was working last weekend to troubleshoot a lack of cooling water circulating through the engine following a freeze. While messing with each and every hose in the water circuit (the engine is cooled with sea water and doesn't have a heat exchange), I noticed the problem.
Specifically, I took off the old hose (bypass hose?) that moves water from the main engine block/cylinder head to the exhaust manifold. When I started the engine, I was surprised to see that not only was there no water, but there was also exhaust or perhaps "blow-by" coming out of the engine side. Putting a thumb over the opening I was able to block it for a bit but a fair amount of pressure built up.
Later I fiddled with the raw-water circuit again and got water and (and subsequently antifreeze) circulating happily through the engine and exhaust manifold again. (I verified this by initially using a clear PVC tubing and could see the liquid coming through that short pipe.)
But the gas going into the water system worried me. I am also getting a fair amount of gas coming out the crankcase ventilation pipe on the top of the engine. Any thoughts on what, if anything, is wrong with the engine?

 

[Michael Davis]

If you have "raw water" and "anti-freeze" you must have a heat exchanger. Exhaust gases should enter the raw water at the mixing elbow. Have you checked your raw water pump impeller? Excess pressure in the oil pan is usually piston rings, out of the valve cover maybe just valve adjustment or a grind.

 

[jssailem]

If you have "raw water" and "anti-freeze" you must have a heat exchanger.

Maybe or maybe not. Not mentioned in the post, but the fellow may have tried to winterize his system. He would have run anti-freeze into the raw water intake. It just did not get throughout the engine and appeared because he had somehow reduced the blocked the cooling lines.
@kloudie1 may be able to give some insight on this issue/condition. It may be as @Michael Davis suggests a valve issue.
Not enough info for me to do anything more than SWAG.

Welcome to the Forum @Will Mauldin all I can say is it is a nightmare and fun working on these small diesel engines. I have a love/hate relationship with my Perkins 4107. Here is a part book with exploded images of the engine you specified. I suspect you used the term "gas" to mean exhaust air and not gasoline. As Michael points out there are few costly "rebuild" type possibilities that might be costly and you may want to eliminate before diving in to the deep end of diesel mechanical mayhem.

 

[Will Mauldin]

Well, the antifreeze isn't normally in the raw-water system, but here in the cold country we put antifreeze temporarily in the engine to avoid having seawater freeze this time of year, which is what I was doing. So no heat exchanger.
Yes, the pump impeller is fine, and in general the raw water system seems to be fine now--maybe there was just a temporary air leak or loose hose that's now fixed.
But why would the gases/exhaust be coming through that opening that's supposed to take water from the main part of the engine to the exhaust manifold? Do the gases and water normally mix, or is there a blown main gasket or something? Would the hypothetical piston rings problem lead to this? Starting is sometimes a problem if the engine is cold and dry, leading me to believe either the piston rings or valves aren't making a great seal in the cylinder.

 

[Will Mauldin]

Thanks for replies, btw!

 

[LeslieTroyer]

bad rings or holey piston is about the only things to cause excessive blow by. "Gas" in the coolant usually points to a head gasket. more info on what you mean by frozen engine would be appreciated.

I agree with @Michael Davis if you have a raw water only cooling - there is no anti-freeze. so there must be a heat exchanger there.

also the bypass hose is the one that jumpers around the thermostat, it comes off the fresh water pump, and goes to just above the thermostat. So don't think it is the

 

[Michael Davis]

Hard starting could be as simple as a faulty or dead glow plug. Small Kubotas just don't want to start without them. Are you saying that exhaust gases are in the raw water before the mixing elbow?

 

[Will Mauldin]

Thanks, Leslie, the head gasket sounds like it could indeed be the problem, as a failure there could link the air/exhaust systems to the cooling system.
What led to my experimentation was that rather than properly winterizing the engine I installed a small heater in the engine compartment, linked to a "smart plug" that I could turn on remotely on cold nights. Well, the smart plug temporarily failed, leading to some freezing, I suspect, that temporarily messed up the raw-water system. I think I have that going fine now, though.
Sorry if I used incorrect terminology--the hose that emitted gases was the one that normally brings water from the engine to the exhaust manifold. It's now healthily moving water again, but the idea that exhaust could be mixed in worried me.
The antifreeze isn't normally there but was just added when I winterized the system last weekend. Normally it's all raw water, no heat exchanger.
So I guess, unless folks recommend otherwise, I'll look for an opportunity when I have time to take off the cylinder head and replace the head gasket. I guess I could check or clean/grind the valves at the same time. Not sure I'm ready to tackle the piston rings yet, but maybe next winter. Have done a lot of reading and work on the periphery of the engine (replaced pump, exhaust, etc.) but have no experience going inside.

 

[jssailem]

Here is a part book with exploded images of the engine you specified.

Opps I forgot to add the file...
Here you go.

Michael the Universal is an Atomic Diesel.

 

[Michael Davis]

Michael the Universal is an Atomic Diesel.

The 5411 I rebuilt in our E-28+ was based on the Kubota Z-500 John. I don't know if Universal used another platform or not.

 

[Michael Davis]

Mine didn't have cylinder liners. Z-500 was stamped on the dipstick. Those drawings in that PDF look a little different than I recall.

 

[Davidasailor26]

How long did you run the engine while you felt air from the hose? Is it possible that there was just air in the line being pumped along by the impeller, or air "downstream" of the water being pumped by the impeller?

 

[Will Mauldin]

Yes, that's the one. Says Z500 on the oil dipstick.
Besides a bad gasket, I guess another way the coolant water and exhaust could be linked is if the sea water corroded through one of its passages, allowing exhaust in Not sure how common that is, and obviously doesn't seem fixable, at least by amateurs. So I'll start with the big gasket and maybe take a look at the valves, I guess.
Then engine starts fine as long as you 1) crank it once or twice, which I've heard spreads some fuel on the piston rings, then 2) hold the glow plug a pretty long time (except in mid-summer) before starting her up.

 

[Will Mauldin]

Oh, Davidasailor26, I didn't even think about that. Yes, I guess the impeller could have been pushing air through. It was a bit smoky, but maybe that was from the impeller smoking or exhaust being drawn in backwards from the my homemade mixing elbow and pushed through the impeller and engine. I was trying all types of configurations trying to get the water going and can't remember what was hooked up at the time or if the thermostat was in place. If that's the case then I feel pretty silly worrying about a complicated engine problem.

 

[Michael Davis]

I usually held the plugs on for 10 to 15 sec. New plugs are pretty cheap if you don't get them from Universal. I did a complete rebuild for about $500 Cdn. including sending the head out for a valve job and doing the rings.

 

[Will Mauldin]

Thanks, Michael. Yes, I've found a replacement glow plug with part number NGK Y103K. I think keeping the electrical connection clean helps as much as anything else.
Did you replace the piston rings yourself? A hard project? Does that involve lifting the engine out of the boat? I guess if you get the cylinder head off and the other appurtenances it's probably not too heavy.

 

[jssailem]

Many parts may be identical.
Found this on the Universal Atomic 5411...

 

[Michael Davis]

The engine didn't run when I bought the boat. I lifted the engine and trans. out and took it home for the rebuild. All new bearings, seals, rings etc. Did it all myself except for the valve grind. Couldn't find a ring compressor small enough, ended up using a hose-clamp for that.

 

[Michael Davis]

That looks more familiar John. Yes Will it was a pretty easy rebuild. It's a very simple little engine. I had never rebuilt any engine before and the thought of doing it was frightening. Looking back I wonder why.

 

[LeslieTroyer]

Clubplug.com had the best GP prices. About $7 each. I think the were ngk.

Also if you don’t have a GP relay you should do that mod it cuts down on the length of time required substantially.