1964-1972 Mercruiser water in oil and in # 4 Cylinder

[ASEAudie]

Hi everybody, I am new here and asking for assistance please.
I did not pressure test the coolant system like i should have, i automatically thought the head gasket was blown, however it looks OK, any suggestions of what to look for.
Thanks Audie

 

[Bondo]

Re: 1964-1972 Mercruiser water in oil and in # 4 Cylinder

Ayuh,.... Welcome Aboard,.... What motor ya workin' on, anyways,..??

 

[TilliamWe]

Re: 1964-1972 Mercruiser water in oil and in # 4 Cylinder

Exhaust manifolds/risers and their gaskets.

 

[ASEAudie]

Re: 1964-1972 Mercruiser water in oil and in # 4 Cylinder

Ayuh,.... Welcome Aboard,.... What motor ya workin' on, anyways,..??

Mercruiser 120 GM inline 4 cyl. S/N# 3331941

 

[Don S]

Re: 1964-1972 Mercruiser water in oil and in # 4 Cylinder

How much water in the oil? Tablespoon or a gallon? Makes a big difference.

A small amount of water may leak past the rings after a while, but if you have major water in the oil (Very High oil level on the dipstick), chances are almost 100% you have a cracked block.

 

[ASEAudie]

Re: 1964-1972 Mercruiser water in oil and in # 4 Cylinder

Exhaust manifolds/risers and their gaskets.

I'll be honest; I have very strong mechanical skills, but mostly with small engines and PowerSports, but customers are pressuring me to do their watercraft things due to the area having the lack of good mechanics or are simply brushing them off.
I have no doubt that I can fix them, I just don't have the experience and skills as some of you here, so any advice or help will not go unappreciated I can assure you of that, Thanks Audie

 

[ASEAudie]

Re: 1964-1972 Mercruiser water in oil and in # 4 Cylinder

How much water in the oil? Tablespoon or a gallon? Makes a big difference.

A small amount of water may leak past the rings after a while, but if you have major water in the oil (Very High oil level on the dipstick), chances are almost 100% you have a cracked block.

Thanks for all the replies you guys,
Not sure the exact amount, but the oil is very milky, so I know this is not good, the # 4 plug was the only one wet with water, upon removal of the head about 1-1/2 cups water on top of piston. Gasket appeared to be just fine. I need ideas of which areas to examine closely.
Thanks again, Audie

 

[Bondo]

Re: 1964-1972 Mercruiser water in oil and in # 4 Cylinder

Thanks for all the replies you guys,
Not sure the exact amount, but the oil is very milky, so I know this is not good, the # 4 plug was the only one wet with water, upon removal of the head about 1-1/2 cups water on top of piston. Gasket appeared to be just fine. I need ideas of which areas to examine closely.
Thanks again, Audie

Ayuh,.... Then go with Tilliam's Idea,...

Pull the riser off the manifold, 'n see if that gasket is leakin'...

 

[ASEAudie]

Re: 1964-1972 Mercruiser water in oil and in # 4 Cylinder

Ayuh,.... Then go with Tilliam's Idea,...

Pull the riser off the manifold, 'n see if that gasket is leakin'...

Thanks, I will give that a look after lunch.
Any recommendations as where to obtain these parts?

 

[Don S]

Re: 1964-1972 Mercruiser water in oil and in # 4 Cylinder

Just curious guys, if the water was laying on top of the piston, how did the oil get "very milky"

If the riser/manifold gasket leaked, all you would get out of the riser is about a cup and a half. That's on top of the piston.
Now where did the water come from that caused the milky oil ?????????? Head gasket is what everyone always hopes for, but seldom if ever is. Remember the Mercruiser Service bulletin on water intrusion?

 

[ASEAudie]

Re: 1964-1972 Mercruiser water in oil and in # 4 Cylinder

Just curious guys, if the water was laying on top of the piston, how did the oil get "very milky"

If the riser/manifold gasket leaked, all you would get out of the riser is about a cup and a half. That's on top of the piston.
Now where did the water come from that caused the milky oil ?????????? Head gasket is what everyone always hopes for, but seldom if ever is. Remember the Mercruiser Service bulletin on water intrusion?

That was exactly my first thought, blown head gasket. Thanks for the Service Bulletin. I will let everyone know what I find.
Thank you guys.
Audie

 

[ASEAudie]

Re: 1964-1972 Mercruiser water in oil and in # 4 Cylinder

Ok, it is obvious that the gasket between riser and Ex. Manifold is bad; which in turn would explain the water on top of the # 4 piston which i assume is the piston located nearest the stern.
The milky oil i am still uncertain about, if the block is bad, where should i look really close before i tell this customer that he will need a new block?

 

[Don S]

Re: 1964-1972 Mercruiser water in oil and in # 4 Cylinder

Drain the cooling system, isolate the block from the manifold and water intake from the drive, and pressure test the cooling system to around 15-20 psi and see if it holds pressure. If it doesn't you might get lucky and be able to hear the leak. If it's internal, you should be able to remove the oil cap and hear it in the valve cover.

 

[ASEAudie]

Re: 1964-1972 Mercruiser water in oil and in # 4 Cylinder

Drain the cooling system, isolate the block from the manifold and water intake from the drive, and pressure test the cooling system to around 15-20 psi and see if it holds pressure. If it doesn't you might get lucky and be able to hear the leak. If it's internal, you should be able to remove the oil cap and hear it in the valve cover.

Thanks Ron,
What if I already have the Head, Ex. Manifold and Riser off of the engine?

 

[Don S]

Re: 1964-1972 Mercruiser water in oil and in # 4 Cylinder

I'm not Ron, but if you already have it apart, it's too late to troubleshoot. Now you put it back together and see what happens.
Personally, at this point, make sure the head and block aren't warped. Put a new head gasket on and torque the head. Then pressure test the block and see if it holds. If it doesn't, something is cracked. But at least you don't have the engine all back together to find out it still leaks.

 

[ASEAudie]

Re: 1964-1972 Mercruiser water in oil and in # 4 Cylinder

I'm not Ron, but if you already have it apart, it's too late to troubleshoot. Now you put it back together and see what happens.
Personally, at this point, make sure the head and block aren't warped. Put a new head gasket on and torque the head. Then pressure test the block and see if it holds. If it doesn't, something is cracked. But at least you don't have the engine all back together to find out it still leaks.

Sorry about calling you Ron,
I will order the needed gaskets, assemble and pressure test as I should have done in the beginning. I will check for warpage although I think it will be fine due to the head gasket looking so good.
Thanks Don

 

[ASEAudie]

Re: 1964-1972 Mercruiser water in oil and in # 4 Cylinder

I got the gaskets, just now noticed the exhaust elbow is rotted out internally! Now i feel really stupid! The ports between exhaust and water are no longer separate due to a large rotted hole, a trained eye would have noticed immediately. The block appears to be just fine.
I'm gonna kick my own butt and start looking for an elbow.
Question? Is this the reason for all the water?

 

[TilliamWe]

Re: 1964-1972 Mercruiser water in oil and in # 4 Cylinder

Probably

 

[Bondo]

Re: 1964-1972 Mercruiser water in oil and in # 4 Cylinder

I got the gaskets, just now noticed the exhaust elbow is rotted out internally! Now i feel really stupid! The ports between exhaust and water are no longer separate due to a large rotted hole, a trained eye would have noticed immediately. The block appears to be just fine.
I'm gonna kick my own butt and start looking for an elbow.
Question? Is this the reason for all the water?

Ayuh,.... As much as We hate to Assume anythin' 'round here,....

I'm bettin', That's a pretty darn Safe assumption.....

Have ya got a picture of the riser/ elbow,..??

 

[ASEAudie]

Re: 1964-1972 Mercruiser water in oil and in # 4 Cylinder

I do, I will put it on here sometime tomorrow, I hope one is available still, this one is toast!
Here is a pic.