Mercruiser 4.3LX - oily coolant

[peos]

Hi,
I spent many hours reading in this forum and learned so much - this is really a great place. Now it's time for my first own question, can't seem to find this one.

I got a 1995 Mercruiser 4.3LX with a closed cooling system. It's hard to start after sitting a couple of days but runs fine once I got it running.
I've noticed there is oil, or at least something that seems to be oil, in the coolant. There also some whit smoke coming out through the hoses
from the valve covers - both sides. Not a lot, just some. I've started to think something is really broken in this motor, headgasket, head - I don't know.
Today I did a compression test, it's 160-170 psi in all 6 cylinders, from what I read that should be fine.
Now I wonder - what could case the oil in the coolant? Should I be worried?

Regards
PeO

 

[alldodge]

Hi,
I spent many hours reading in this forum and learned so much - this is really a great place. Now it's time for my first own question, can't seem to find this one.

I got a 1995 Mercruiser 4.3LX with a closed cooling system. It's hard to start after sitting a couple of days but runs fine once I got it running.
I've noticed there is oil, or at least something that seems to be oil, in the coolant. There also some whit smoke coming out through the hoses
from the valve covers - both sides. Not a lot, just some. I've started to think something is really broken in this motor, headgasket, head - I don't know.
Today I did a compression test, it's 160-170 psi in all 6 cylinders, from what I read that should be fine.
Now I wonder - what could case the oil in the coolant? Should I be worried?

Regards
PeO

Howdy

Sure could use your engine serial number.

I wouldn't worry to much with being hard to start after a couple days. While its not great but with no other starting issues I would deal with it unless you want to get into rebuilding the carb. Its probably just loosing gas out the carb so it needs to refill before starting. Now if you have an electric fuel pump then well maybe we need another look.

If oil is getting into the coolant you need to look into that. Your engine should have power steering, is the oil in it getting low?

White smoke out the valve covers could be water and blow by. Has the oil been changed this season?

 

[Scott Danforth]

welcome aboard.:welcome:

condensation will cause vapor out the breathers.

however a pressure test of the cooling system will let you know if you have a breach (cracked head, cracked block, or bad head gasket.)

 

[peos]

Thanks for the feedback. Serial is 0F439501. I actually did a rebuild of the carb (4BBL Weber 9600) last winter, after watching lots of good instructions from youtube. I do believe the carb is in good shape, choke is working, closing as it should and pull-off is ok. I also put in a switch to be able to prime the carb before cold-starting, again after reading about that here. Works like a charm - what a great tip! The fuelpump is old and was giving me some headache this spring. I pulled it out and ran 2-stroke oil through it for a while and after that it's been working fine. Which can be verified by using the prime-switch and listen. Guess I should replace it this winter - but that's not causing the issues I'm seeing. I did change the oil and plugs during winterization last year and have been running the boat for some 20 hours this season, so it should be OK. When I look at the stick it's clear, a bit dark and near the full line, no change over the season.
I haven't checked the level in the power steering - thanks for that one - will check tomorrow!
Pressure test of the cooling system seems to be next step. I've never done that though. I guess it's just putting some preassure in there and listen around and see if preassure drops over a couple of minutes. Are there any hints of what preassure to use and how much it can drop over a few minutes and still be acceptible? Or am I completly wrong here??

Again - thanks for all feedback!
/PeO

 

[Bondo]

Are there any hints of what preassure to use and how much it can drop over a few minutes and still be acceptible? Or am I completly wrong here??

Ayuh,..... Welcome Aboard,.... Stant makes a nice coolin' system tester, for cars, ya use it in place of the rad. cap,...
I've got one I've had for years,...

Pump it up to 'bout 10/ 15psi, 'n it should hold almost indefinitely,...

 

[peos]

10-15, indefinitely it is. Will test next weekend when I'm at the boat. Thanks!

 

[peos]

I had to pick the boat up from the lake since it's getting cold, and winterize it. I did a quick pressure test on the coolant system. It seems to hold pressure good so I've decided to let it sit over winter and see next season. I need to work on the drive and some other things over winter. More threads to read and stuff to learn.
Thanks for the support guys!!

 

[alldodge]

Look forward to hearing the results next season