Chocolate Oil in 7.4L Mercruiser

Hello folks! Last September I purchased a 1988 Searay Sundancer 268 with a 7.4L Mercruiser, raw water cooled. In October of last year when I checked the oil I noticed that the oil had become chocolate in color and I had gone high on the dipstick by about 1/2-1qt. The engine continued to run perfectly, not spitting any foamy junk out anywhere. I'm sure the last owner had not replaced the exhaust manifolds or risers so that makes them at least 4 years old (will replace them). I also noticed a small amount of bubbles coming from between the intake manifold and the head. I had a mechanic tell me over the phone that the intake manifold is a common problem with this engine, has anyone else heard this? Any ideas/thoughts?????????????

Also, I tried to change the oil with an electric pump but couldn't get more than a couple qts out through the dipstick tube. I only warmed the engine slightly for fear that I would damage something. Am I doing something wrong or does it just take forever?

I've seen several threads about the chocolate oil but wanted to put my situation out there to see what you all think.......I've been really impressed with this site! Lot's of great info!!!!

Jim
Baltimore (Canton), MD

Re: Chocolate Oil in 7.4L Mercruiser

""The engine continued to run perfectly""
Why are you running the engine after you discover that your oil has water ?

Re: Chocolate Oil in 7.4L Mercruiser

I started the engine to fog it.

Jim

Re: Chocolate Oil in 7.4L Mercruiser

You should have been starting the engine LAST YEAR, to warm it up so you could change the oil. No sense fogging a motor that has water in the oil that is in and on the crankshaft, camshaft, main, rod, and cam bearings, gears, timing chains, valve lifters, rocker arms, etc.

Re: Chocolate Oil in 7.4L Mercruiser

Thanks for the advice Don.....you got a time machine I could borrow?

Re: Chocolate Oil in 7.4L Mercruiser

I wouldn't worry about getting the oil out right now, what you need to do first is find out WHY you have water in the oil. Block of the water hoses going to the manifolds and/or risers and pressure check the block. If it holds pressure, you may have lost the oil cooler which will allow water into oil when the engine isn't running.
Might want to check the oil cooler first.
After you find what is leaking, then pull the engine and take it apart and inspect everything for water damage.

Re: Chocolate Oil in 7.4L Mercruiser

I just recovered from a bad case of chocolate milk oil in my 4.3L Mercruiser.

After replacing the manifolds (from one piece to two piece), the head gaskets, and the intake manifold gasket, I was good to go. However, throughout the process I prayed I did not have a have a cracked block. Also, I had my heads magnaflux tested to make sure they were good as well.

Basically it comes down to one or more of the following:

1. Bad Exhaust Manifolds (almost for certain)
2. Cracked Head
3. Blown Intake or Head Gaskets
4. Cracked Block

If it is cracked block I suggest looking for a new motor or remanufactured. There is a guy on ebay who sells motors out of S. Florida for Like $1400 shipped (but that is for the V6, not sure about V8). Someone will post a link I'm sure..

Regarding the oil, the electric pump should be fairly quick. I have a manual pump and it takes forever to get it out, but it eventually comes out. The warmer the oil the faster it will come out.

Re: Chocolate Oil in 7.4L Mercruiser

Thanks guys! Gonna start the teardown this weekend!