Detroit Diesel 6-71 Oil in Coolant

Hello

First off I'm used to working on outboards but no experience working on diesels.
My nephew bought a boat and when I went down with him to check the fluids today 1 of the engines had a oil in the tank on the top of engine where the coolant get replaced.

Iv'e done alittle searching around but can't pin point posts about the 6-71 and firgured I'd come here.

Iv'e seen a few posts saying that it could be head gasket , oil cooler leak , cracked head/cylinders. What else whould I check that could give the engine these symptoms? Wouldn't a compression test eliminate a head gasket or cracked heads/cylinders? If so what PSI should each cylinder be?

The previous owner said that he recently replaced a gasket that fit between the engine block and the cooler and that it was pressure tested and held about 50lbs. He 'thinks' it could be either the gasket blew out again or old oil left in the system when the first oil cooler gasket blew out, that wasn't totally cleaned out.


Thanks,
DamianJP

Sometimes this can be a tough question to answer. Most of the time, oil in the coolant can be traced back to a cracked oil cooler but, as you already stated, it could be from someplace else.

The previous owner could be right about left over oil from a poor clean up of a prior failure. That is my first question. Are there traces of oil coating the surge (expansion) tank and "spotting" of little blobs on the surface of the coolant? If so, a bit more clean up might be in order. Flushing a cooling system of oil in a boat is a messy affair at best. After a good flush, you need to operate the engine and monitor the coolant to see if the oil returns.

However, if the oil you see is beginning to make a gray "milkshake" liquid of the coolant, then you are most likely looking at an oil cooler. I'm not sure what the previous owner meant when he stated that a gasket repair would be tested at 50 psi. The cooler core itself is normally bench tested at around 50 psi since that is the design oil pressure maximum for the engine. One thing to consider though is that the oil pumps on these engines can produce a great deal of oil pressure and a pressure regulator or a pressure relief valve that is stuck can spike the oil pressure to over 100 psi and blow the cooler. Operating oil pressure tests should be performed any time a cooler core is suspected of failing.

Monitoring the engine oil for coolant contamination is also paramount as the oil can be cross contaminated after shutdown because of cooling system pressure being greater after the engine is stopped. Is she running a pressure cap? Ethylene glycol? Need to keep an eye on that.

My knowledge of the inline 6-71 was pretty limited even when I worked on them everyday and the memories are fading fast. I only have literature for the V-71 and V-92 anymore. But, I can tell you that performing a compression test on these engines is a bit more involved than on a typical gasoline engine. Some very specific knowledge, tools and skills are needed to do a proper compression check and it usually takes even a practiced tech the better part of a day to do one.

Each injector needs to be removed individually to install the gauge and then the engine is started and run at 600 rpm. That injector is then reinstalled and you move on to the next cylinder. Acceptable pressures are generally between 400 and 500 psi depending on engine condition. Not saying don't attempt it, just be prepared and know that you will need specific tools and procedures to do this work.

I read your other post and I can only say that I always purchased my service manuals through the local Detroit Diesel distributor. That is where I would ask about getting some documentation. These engines haven't been manufactured for many years now but there are still a stink pot full of them still chuggin' away out there. If you haven't checked Ebay for manuals for sale, that might be a place to get a bargain one.
Good luck.
jimmyd

After you clean the cooling system, add some leak tracer to the crank case. If oil appears in the cooling system again, hit it with the black light, if the oil glows it's leaking, if not, you need to clean it again.

Damian,
I took my own advice and looked on ebay motors and found this. This might be all you need. Well, this and a tool box full of Kent-Moore tools and the spirit of an old timer Detroit Dripper mechanic looking over your shoulder. HTHY.
jd

http://cgi.ebay.com/ebaymotors/Detr...Motors_Manuals_Literature&hash=item45f7844bd7

oil in cooling system is from the oil cooler, not a gasket

Hey guys

jimmyd-
Good news-no coolant in oil ,seems like left over mess someone left us with. Looked like the little blobs like you said. I hate when people do stuff half-assed. We ran the boat to the destination today for 4 1/2 hours straight and man.... for a 50 yr old engine with only 1 major rebuild these motors rock !! Had a small oil leak from the two lines leading and exiting the oil filter housing (prolly the two o-rings) and we found out the previous guy had bent the starboard side engine's valve cover abit. It was leaking oil abit and we had to add some as we ran. Thanks about the manual man !! For $15 it's worth its weight in gold.

Is there no online schematics for part numbers and such? I might need a valve cover if a trip to a machine shop can't straighten it.

Dockside-
Thanks for the leak detector tip.Gonna pick some up and a cheap black light at harbor frieght.

Marv-
Your right, I meant the oil cooler held 50Lbs. But I didn't know that the gasket breaking would not promote oil in the coolant, Thank you.

Thank you all for responding, I'm heading back to the boat tommarow, I'll let you know whats up.



Thanks again,
DamianJP

And, for $99 + $6 shipping you could have the "real deal".

http://cgi.ebay.com/ebaymotors/DETR...Motors_Manuals_Literature&hash=item5added9c0c

Not sure about the old in-line but they started making cast aluminum replacement valve covers for many of the old engines as the stamped sheet metal ones never sealed very good even when they were straight. Probably cost a pretty penny though. I hope you and your nephew get a lot of enjoyment out of the boat. Them old two cycles drip and clatter and smoke and spit fire but they take a lickin' and keep on kickin'.

Thanks again Jgmo

I found a site for good schematics and parts

http://www.powerlinecomponents.com/catalog/il71_alpha_index.htm

Check the rocker cover section when ya get a chance, no price breaks $210 which is good I guess.

I also need to o-rings and a small gasket that goes on the oil filter housing. Theres 2 lines that come from the housing end and are leaking abit of oil at lower oil PSI's. Can't find the schematics section tho. Have you seen these oil filter housing before? It's not vertical oil filter at top but around the starter level and at the front end of the engine. It holds the filter horizontal.

Thanks again ,
DamianJP

Glad all has worked out. Just remember, "If it's not leaking oil, there is no oil in it!"

Good luck!

Well, like I said before, my memories of the inline engines are few and fading and there are probably as many configurations for oil filter adapters as there are boat models.

Are the two lines you are talking about open ended? If so, they would be your air box drains and you don't want to stop them from "drooling". If they aren't the drains, then maybe you could post a picture of them and someone here might be able to help you identify them. Start a new thread though as this one is getting long.

Speaking of the drains, they do need to be kept clear so that the air box doesn't fill with ring slobber and then reintroduce the oil into the combustion chamber in slugs of liquid that could cause damage and carbonizing. So, if you don't know what/where they are, find them and make sure they have air coming out of them. Many boats with Detroits in them use "catch" basins or simple cans to keep the air box drain oil out of the bilges. They need to be monitored and emptied regularly. There is also a system called AirSep that reintroduces the oil to the engine for combustion but I've never had the pleasure os messing with one. I think those systems are only for turbo engines.

Another point of venting that sometimes produces a bit of oil drool is the crankcase vent. This too needs to be kept clear and an oil catch is sometimes associated. If the crankcase is venting to the engine room atmosphere, there should be a ventilator running to prevent vapor build up much like a gasoline engine installation.