Help: Mercruiser inline 6 water in oil

[SRV190-NL]

Hello all

I'm currently working on the restoration of a Sea Ray SRV190 with a 4.1L/250CID Mercruiser/GM engine.

Work in progress pics here

After replacement of the bellows and hoses in the transom area I ran the engine with a water hose connected to the outdrive. The engine started at the first turn and ran perfectly. After about 10 minutes I turned the ignition off and it was time for oil change before winter storage. But when I pulled the dipstick the oil looked milky which is of course bad news. I extracted all the sludge, almost twice the amount that you would expect when draining the oil. I don't know what caused water contamination of the oil. It may be the exhaust manifold/riser, or a crack somewhere or a gasket.. maybe you experts can share some experience on this matter. As said, the engine ran really nice, even after 6 years of storage, and the spark plugs looked pretty good when I removed them. I cranked the engine for a few seconds with the starter and found no trace of water in the cylinders.

I tried to remove the exhaust manifold but one of the bolts (second from front) is really stuck and after cutting the head of the bolt the manifold still doesnt want to let go. It's a real pain. Do you have any ideas on that?

Anyway, its a real bummer. The boat is now finished and I did not expect the engine was going to cause any problems.

Regards and thanks for any tips you may have for me.

-Jan

 

[NHGuy]

Re: Help: Mercruiser inline 6 water in oil

The manifold is a good item to check, but as I understand it manifold leaks are more likely to be the cause of water in cylinders. I believe you will want to rebolt the manifold and check for cooling system integrity with air or water pressure. You block off the cooling system on one end and pressurize the other end, then listen at engine, head, exhaust and carb for air.
Stay tuned, others with more knowledge than me will be along soon. They may also know common fail points on your specific engine too. Good luck, I hope your repair is a small one!

 

[Bondo]

Re: Help: Mercruiser inline 6 water in oil

maybe you experts can share some experience on this matter. As said, the engine ran really nice, even after 6 years of storage,

Ayuh,... My guess is a Cracked Block....

If it were the exhaust manifold, the sparkplugs would show signs of water...

 

[SRV190-NL]

Re: Help: Mercruiser inline 6 water in oil

>but as I understand it manifold leaks are more likely to be the cause of water in cylinders

That was my thought too and I found no trace of water in the cylinders and the the fact that the engine ran really well confirms that. The boat/engine has been in storage for 6 years, as far as we know completely drained. But the waterpump turned out to be seized and has been replaced as well as the thermostat/housing. See the attached pics.

 

[Don S]

Re: Help: Mercruiser inline 6 water in oil

as far as we know completely drained.

It probably was drained after the first winter when the block cracked.
The only way you would get that much water in your engine, in that short a time, on the muffs is with a cracked block. Pull the push rod covers off the side of the engine and look for cracks and water. Bet you find your problem.

 

[SRV190-NL]

Re: Help: Mercruiser inline 6 water in oil

It probably was drained after the first winter when the block cracked.
The only way you would get that much water in your engine, in that short a time, on the muffs is with a cracked block.

Makes sense to me. It was an awful lot of water and the oil looked good before we ran it..

I checked some local auction sites and found several old 250CID chevy engines. These are car engines but on the pictures they look the same as our block. Do any of you know if such car blocks can be used? I know the marine versions have a different camshaft, but are they otherwise the same?

Many many thanks

 

[Bondo]

Re: Help: Mercruiser inline 6 water in oil

Do any of you know if such car blocks can be used? I know the marine versions have a different camshaft, but are they otherwise the same?

Ayuh,... I wouldn't worry about the Cam,...

What you DO have to look for is the motor mount, mounting Tab on the forward starboard side corner of the block...
Many, Many blocks Don't have it...
Some do...

 

[ziggy]

Re: Help: Mercruiser inline 6 water in oil

understanding that i'm not the pro and mostly just like to read.....

from s/m #2. "6 cylinder blocks crack on the sides of the engine, just below the core plugs or along the upper edge below the cylinder head."

that said, i have a L6 block in my garage that has a crack in it on the ft. of the block. it extends from the circulation pump opening to the ft. port head bolt. why mine cracked there, i've never figured out.

from memory and reading iboats a lot..

some L6 blocks don't have a mounting boss on the starboard side for mercrusier ft. motor mount. some folks have got around this by making bolt on boss or welding on a boss.

i also understand a truck cam is ok for marine application. a car cam is not.


another fwiw. my L6 that had a 15 year lay up had a bum manifold. rust on the outside. rusted through on the inside. out come was water in the oil. can't remember if i had water on the plugs or not. i may not have even checked. my symptom was hard starting one day. checked my oil and it was overfull and chocolate milk. i just assumed manifold i think. since it looked questionable from the outside. and it was the manifold in my case.

 

[SRV190-NL]

Re: Help: Mercruiser inline 6 water in oil

Ayuh,... I wouldn't worry about the Cam,...

What you DO have to look for is the motor mount, mounting Tab on the forward starboard side corner of the block...
Many, Many blocks Don't have it...
Some do...

Thanks for the tip, I will definitely check te mounts. I read a marine vs car engine thread on another forum and the message is that the blocks are the same except for all the stuff bolted on, including alternator, generator, water pump, starter etc.

I ask all the sellers of the engines the casting number of the block. I suspect when the castings are the same, the mounts will be the same too ;-)

(added picture: This is the tab we are talking about, right?)

 

[Bondo]

Re: Help: Mercruiser inline 6 water in oil

(added picture: This is the tab we are talking about, right?)

Ayuh,... That's Correct,... Without those 2 bolt holes, you'll have serious problems...

 

[SRV190-NL]

Re: Help: Mercruiser inline 6 water in oil

Ayuh,... That's Correct,... Without those 2 bolt holes, you'll have serious problems...

For what I can see, it does not even seem too hard to weld a tab on. I could make some sort of mold of the tab's exact position on the old engine before sawing it off ;-)

 

[Fishermark]

Re: Help: Mercruiser inline 6 water in oil

Welding will not hold on cast iron... but JB Weld, or some other epoxy does. Here's what I ended up doing:

Here's the link with a few more details: No mounting tabs on inline six

 

[SRV190-NL]

Re: Help: Mercruiser inline 6 water in oil

Update

I found a complete engine for sale including carb, generator, manifold, riser, starter, mounts and everything with a decent price tag. On the pics it looks very good and the seller claims it runs great (but so does our cracked engine). See attached pics. I'm driving up there next saturday and will test the engine as good as possible for compression, cracks etc. Hopefully the engine is as good as advertised cause its a pretty long drive. I can always look for a good used lower block later on and rebuild the old engine whenever spare time allows it. Many many thanks for your valuable input and if you have any extra tips and hints on test procedures for the "new" engine, please let me know. Will keep you posted.

Regards

-Jan

 

[Fishermark]

Re: Help: Mercruiser inline 6 water in oil

Certainly looks good.... sounds like you have a good plan. Good luck!

 

[SRV190-NL]

Re: Help: Mercruiser inline 6 water in oil

Spring has arrived and a new engine for the boat. The engine in my last post was a lemon. I found a very nice 79 engine and we dressed and tuned it in the winter. Aligning took about a day, but we have a nice result.

Pic of the engine here http://www.flickr.com/photos/29481933@N08/5582531542/

And a video of the first startup http://www.flickr.com/photos/29481933@N08/5582528682/

Final checks next weekend... almost complete!

 

[kilowatts]

Re: Help: Mercruiser inline 6 water in oil

Hi Guys:

Great looking motor. I just love to see the "Big Six" in a boat. Good luck.

kilowatts

 

[HT32BSX115]

Re: Help: Mercruiser inline 6 water in oil

OMGWTF!!


That is a REALLY NICE looking Searay!!

If you "restored" it, that's a NICE job!!

Hope the "new" engine works well!

Spring has arrived and a new engine for the boat. The engine in my last post was a lemon. I found a very nice 79 engine and we dressed and tuned it in the winter. Aligning took about a day, but we have a nice result.

Pic of the engine here http://www.flickr.com/photos/29481933@N08/5582531542/

And a video of the first startup http://www.flickr.com/photos/29481933@N08/5582528682/

Final checks next weekend... almost complete!

 

[SRV190-NL]

Re: Help: Mercruiser inline 6 water in oil

OMGWTF!!


That is a REALLY NICE looking Searay!!

If you "restored" it, that's a NICE job!!

Hope the "new" engine works well!

I restored it with two friends over the past year. Over 1000 hours wordt of labor and just about everything on the boat is new.

Our Sea Ray is launched next saturday, champagne and cheers. Hope the weather will be fine too.

Will post pics of this milestone on flickr. We got the re-upholstered engine cover back yesterday. It looks very nice. I'm all excited about the launch. Hope everything goes well!