CAT 3208 coolant in oil

Last December we had a major overhaul on the port engine. This was due to a leaking after cooler issue which hydraulically locked the engine on startup. The engine is a 3208TA 375 and currently has 250+ hours since the major with 1650 hours total time.

Since I did not get the opportunity to use the boat much over the winter I only put less than 20 hours on the engine until our summer trip at the end of May. Just before the trip I changed the oil in that engine (Caterpillar and the mechanic recommended 50 hours) and after speaking to the mechanic who did the work and to Caterpillar I decided not to do an oil sample due to the low time on that oil. Just did not want to change it during the trip.

Our trip up the Tenn-Tom lasted 15 days and resulted in close to 80 hours engine time plus the additional hours we ran the boat while in Tennessee for the summer. By the time we were ready to make the return trip the engine hours had on that oil had exceeded 150 hours so I decided it was time to change it and sample it. I also at that point checked the coolant tank and estimated it to be about 1/2 gallon low on coolant. This was added before the return trip.

While on the return trip I received the results back via email for that engine indicating that there was coolant intrusion into the oil. This was indicated by the fact that excessive copper, sodium and potassium was present in that sample. When I inspected the engine during a routine morning check the next day before departing the coolant level was fine with no loss.

This same day we were held up by a lock for 3.5 hours. So, in order to make up some time to the next anchorage I pushed the boat up from my normal 1400 rpm cruising speed to 2200 rpm for about 2 hours. Again the following morning during routine engine checks before departure the coolant level was again 1/2 gallon low. I will also add during the previous days's running the engine has never run hot nor has steam been observed from the exhaust plume.

Durning the days remaining on this trip until we returned the boat was run at 1400 rpm until the last day in when which I ran the boat about 30 minutes at 2200 rpm before entering the marina.

I've checked the coolant since arriving and there is no indication that it has lost anymore coolant since the hard 2 hour run several days earlier when coolant was added and the additional 30 minute run before entering the marina.

So I guess I am looking for suggestions on where to start looking for coolant leaks. I did pull the oil drain plug after 24 hours of sitting to see if there was any indication of coolant in the bottom of the oil pan. There was none. I also retested the oil with a second sample just in case there may have been some type of lab mistake. Today I received the results and the sample again tested positive for the contamination.

First I suggest posting this on boatdiesel, but condense it to the facts: loss of coolant at high rpms, none at low, no change in oil level- true?, oil analysis findings, etc. The pros on boatdiesel don't like to read a lot of words.

But here are my observations:

Oil and coolant almost always go the other way- oil into coolant not the other way as the oil pressure is higher than the coolant system pressure. Also can you please post your oil sample result. If it is Blackstone and maybe others AFAIK, they infer coolant in the oil from metals content and in a marine engine sodium and potassium are mostly caused by sea water, not coolant. This is another problem if true, but let's look at the oil analysis first, but also note the next paragraph.

Also was the overhaul done in the boat? The reason I ask is that if you did not completely drain the oil from the crankcase (with the engine removed and the pan off) then it takes 3 or more changes for the sodium and potassium to return to normal after a sea water event. Ask me how i know this.

But that doesn't change the fact that you are losing coolant. Maybe as a result of a bad head gasket that is allowing coolant to pass into the combustion chamber and out with the exhaust gas or as a result of a cracked exhaust manifold. But you said you don't see any steam. How about at high power and at high power do you smell an antifreeze smell (I don't know what that is myself but others have reported it).

Also check the coolant overflow bottle for bubbles in it while running at high rpms. That is a sure sign of a bad head gasket.

David

Latest oil sample

Here is the latest report. I did put a bottle on the overflow hose trying to catch coolant but have not tried putting fluid in it and looking for bubbles.

Jon

Who did the overhaul (using authentic Cat parts and gaskets etc) and is it covered by warranty? As Dave suggests, boatdiesel should offer some expertise.

OK, it looks like your lab actually does measure antifreeze. Also the K is high and the Na is lower. If it were the result of seawater it would be the opposite. So, not likely seawater.

But I will bet if a couple of gallons of antifreeze had leaked into the oil, the Na and K values would be much higher and you would also see the oil level rising. So most of it is going out the exhaust IMO and with antifreeze in the exhaust and oil, that is almost certainly a bad head gasket.

If you just have a coolant overflow tube, then put it in a bottle of water so you can see bubbles. You will have to do it under load at 2,200 rpm as it only seems to leak at high loads- another indication of a head gasket (or manifold crack).

If you post on boatdiesel, the guy you want to respond is dave, a real Cat guru. He can be a little terse but I have never seen him give bad advice. You want to start a conversation with him rather than let him give a quick diagnosis. He really knows Cats.

Ski who frequents this site as well as boatdiesel is also a good resource. Clark is also a good guy on boatdiesel.

David

sunchaser said:

Jon

Who did the overhaul (using authentic Cat parts and gaskets etc) and is it covered by warranty? As Dave suggests, boatdiesel should offer some expertise.

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The work was done by a very reputable company in south Mississippi. Warranty was 6 months on the machine work and one year on labor. All the parts were genuine CAT parts and those carry a one year warranty.

I also posted this over on boat diesel. I've searched the CAT information over there and really did not find anything I felt related.

I don't know about the cats, but exhaust manifold to turbo leaks are common on some other engines. I have struggled with coolant loss issues on my Deere, with no physical leaks, and no accumulation in the oil. The diagnosis has been turbo flange seepage, with the lost coolant going up the stack unnoticed. This past fall I replaced the gasket again, but this time sealed with Permatex magic red goo at the advice of a Deere/Luger expert who I really trust. I suspect that some cross contamination with oil is possible there as well, but am not certain. Regardless, I'd start with the turbo before pulling the head to replace the head gasket.

Also, maybe just do a coolant pressure test? Pump up to just below the relief pressure, and let it sit for a few days, then inspect inside the turbo throat for signs of coolant.

On, one other thing. Depending on where in the oil system path the oil cooler is located, coolant could flow into the oil. This would happen if the oil side is in the oil return which is at or near atmospheric pressure, so lower than the coolant pressure. It's another one of those engine-specific things that needs to be looked into.

Seems to me that on the 3208TA if coolant was leaking in the throat of the turbo housing it would go right out the exhaust. I might be wrong and maybe someone will chime in with more experience. As for the oil cooler it was replaced during the build. Maybe the O-Rings where it is pressed into the housing were pinched or cut on install. I'll wait until maybe Ski or someone else chimes in before tearing things apart and pressure testing.

Double check that your invoiced part numbers agree with Cat's part numbers. especially for gaskets. I have seen where aftermarket non-OEM Cat gaskets are not the same and can be problematic. 3208 Cat head gaskets are leak coolant points after a few decades, maybe the new ones are too.

I'd suggest having a Cat certified tech come in before you start tearing into things. What does your rebuilder say? Are they being supportive or wanting to wash their hands?

Since you are posting same on boatdiesel, ask there who is the 3208 Cat certified go to guy in your area. Being marine certified is more than a sign in the window.

Last but not least, a hydro locked engine can result in damage in many places. Who did what for the initial engine damage assessment may need to be revisited?

sunchaser said:

Double check that your invoiced part numbers agree with Cat's part numbers. especially for gaskets. I have seen where aftermarket non-OEM Cat gaskets are not the same and can be problematic. 3208 Cat head gaskets are leak coolant points after a few decades, maybe the new ones are too.

I'd suggest having a Cat certified tech come in before you start tearing into things. What does your rebuilder say? Are they being supportive or wanting to wash their hands?

Since you are posting same on boatdiesel, ask there who is the 3208 Cat certified go to guy in your area. Being marine certified is more than a sign in the window.

Last but not least, a hydro locked engine can result in damage in many places. Who did what for the initial engine damage assessment may need to be revisited?

Click to expand...

With the above, I would notify the shop that did the work so you can keep the warranty active.

djmarchand said:

...- oil into coolant not the other way as the oil pressure is higher than the coolant system pressure...
David

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but cylinder pressure is higher than both, yes? And pan and valley are lower pressure than coolant jackets (e.g. a cracked block will leak coolant into oil).. Head gasket? Maybe try retorque?

Head gasket can weep coolant into crankcase passages on head deck. Not unheard of, but usually on old high hour engines. Should this happen on a rebuilt, there should be some discussion of warranty. Whether it is expired or not, that is between you and the shop. But a fresh rebuild should not be getting coolant into the oil.

So as I understand it, you ran some, took a sample and changed oil at the same time. Sample came back high in Na and K. Ran 114hrs, new sample also came back high in Na and K. So two high samples, and an OC between. And losing coolant. Both point to a valid leak, but not with certainty.

A few q's: Was engine built out of the boat in shop conditions? Or built in the boat? Were all parts cleaned or is it possible some milkshake was hiding in places like oil cooler and block?

Were you topping up coolant in the steel tank each time? And was there a recovery bottle attached? If you top up that engine cold, it will blow out a qt or two due to thermal expansion when it heats up. If you have a recovery bottle the expanded volume should go in there with heat up, then back into the steel tank with cool down.

With no recovery bottle, coolant level in the steel tank should be an inch or two down and stay there. Topping up is pointless as the extra will be blown out.

Any milkiness looking into oil fill cap? Or on bottom of cap?

Just trying to make sure the coolant was actually going into the crankcase and not going into the bilge.

I would start with a simple cold pressure test. No need to take anything apart. See if you loose pressure. I like to use a set up that I can block off and let it sit over night.
I think that the guys who built this need to be informed of your worries. I would think that they would be more than happy to do a pressure test for you. Just my thoughts. YMMV. Bryan

Ski, as to the head gasket I have a question. I see some streaking coming from behind the exhaust manifold down the side of the block. I try and take some pictures and post them next week. This I can make out using a mirror to look up under it.

As to everything else you stated to the timeline it it is correct. As to your other questions the engine was taken apart in the boat. Had to do this to get it out. The short block was rebuilt in the shop and then returned to the boat where the heads, etc were installed inside the engine room. The block was bored and sleeved on on one cylinder. So the block was vat cleaned and so were the heads before they were reworked. The oil cooler was replaced as the builder would not warranty the job without all of the oil hoses, cooler, and oil filter and oil pump being replaced. So I cannot see how anything could be hiding.

As to topping off the day tank it is only filled to the bottom of the throat tube in the tank. I did put a bottle on the end of the overflow tube. This gives it about 1 1/2" of room inside the tank for expansion. There has not been any fluid captured in the bottle. Also no moisture present on the oil filler plug. So this means so far 1/2 gal of coolant has escaped over the course of the 114 hours somewhere? The oil level has never increased and during that 114 hours I have added about 3 quarts of oil. Both new and old engine seem to use a quart every 35 hours or so.

As to the questions about genuine CAT parts, I personally walked into the dealer and purchased all of the parts needed for the build. So they are the real thing.

Warranty is not the issue. The shop and the mechanic who did the work are willing to stand by the written warranty. Issue is the boat is 100 miles away from them and it's a days run over there. Then I have to find a marina willing to take me short term that is close enough to the parties involved.

So, if it is something that hiring someone local to take care of for two boat bucks or so it works out to be about the same dollars all the way around. The problem here is the same as going over there. It will be on someone's timeline when they can get to it. Seems all of the good mechanics stay booked up. I am waiting for a call back next week from a mechanic that several of the local marina personnel have recommended. I could do this myself but I really prefer not to as I just don't have the tools anymore or really the time with everything else I have going on.

Also what is the thought on re-torquing the head?

Bryan, the mechanic who did the build also discussed with me the pressure test. However he told me that it was best to remove the oil pan. By doing this it might be possible to detect where the leak is coming from.

No fan of re-torquing, but have done it on older engines where clamping force was known to have relaxed. Never on a new build, that should be right from the git-go.

Stain from head joint is a good clue. Should not be there.

I'd have them pull the heads and absolutely double check block and head deck surface finish, cleanliness, flatness and bolt condition and bolt hole cleanliness. I may be sloppy in some ways, but when I build an engine I am anal about the above. Have seen other mechs that are much less anal and just don't get it about getting things to seal. Never had a callback on an engine build leak. Maybe a hose, but not the base engine.

After cleaning bolts and bolt holes, I run a bolt in each hole to check for good threading.

clean clean clean!!

Regarding warranty, it may require you getting the boat into their 'hood, or for you to pay travel/lodging. Probably best to get the boat down there. Depending on how warranty is worded. You would probably get a better quality job if it was there. Mechs not tired, shop nearby, no rush. Maybe you ask them if they know of a local slip. In my area, the shops often know of a customer that has left for the season and have no problem with it being used as a shop slip for a while.