Water in oil/ Blown exhaust Manifold?- Newbie needs advice

[canuto]

I have a problem 1975 SeaStar I/O GM 4 cyl 165HP I think I might have a couple of major problems but need advise. The motor ran fine before I shut it down due to overheating(used Muffs on stern drive). I next removed hose to exhaust manifold and placed waterhose going into exhaust manifold from thermostat, to see if that would cool down motor. No difference. PLZ don't laugh too loudly here.

Do U think the Mercrusier sterndrive might need an impeller which might have been the primary problem causeing the motor to overheat or water pump? The water pump with removed thermostat , did not circulate water while running. Today, I removed it and it rotates easily off the motor.

Someone suggested Blown Headgasket.-
I removed the head and can't really tell by looking but I did find water in the first piston and appears might be coming from exhaust manifold. I poked my finger into the first outlet in the exhaust manifold and it had water. Can a leaky exhaust manifold be the problem?
I have pics and someone might be able to advise what my next steps should be. I'm kind of clueless?
Pls advise. Pics for exhaust manifold and head

 

[Don S]

Re: Water in oil/ Blown exhaust Manifold?- Newbie needs advice

Those engines have a closed cooling system so a blown head gasket would have put antifreeze (if AF was actually used) into the cylinders. Of course it could be a bad manifold, or even a bad heat exchanger tht allowed salt water into the engine. But being a 75, I don't see it being in salt water.
You are probably suffering from manifold, riser or riser gasket problems.

 

[Haut Medoc]

Re: Water in oil/ Blown exhaust Manifold?- Newbie needs advice

Welcome to iboats...

 

[Haut Medoc]

Re: Water in oil/ Blown exhaust Manifold?- Newbie needs advice

Whoops!
First, there is no 4 cylinder Gm engine that is 165 HP...
I think you have a model 470....
If you have a radiator looking thing that has anti-freeze, then it is a 470.......
You would experience coolant loss & would see anti freeze in the cylinders, if it were a bad head gasket....
From the look of the rust, I think you have a bad manifold/riser or connection between the two.....
If you don't know the impeller's age, it is time for inspection......
More than 2-3 years old bears inspection......JK

 

[canuto]

Re: Water in oil/ Blown exhaust Manifold?- Newbie needs advice

Whoops!
First, there is no 4 cylinder Gm engine that is 165 HP...
I think you have a model 470....
If you have a radiator looking thing that has anti-freeze, then it is a 470.......
You would experience coolant loss & would see anti freeze in the cylinders, if it were a bad head gasket....
From the look of the rust, I think you have a bad manifold/riser or connection between the two.....
If you don't know the impeller's age, it is time for inspection......
More than 2-3 years old bears inspection......JK

 

[canuto]

Re: Water in oil/ Blown exhaust Manifold?- Newbie needs advice

Apologize for the Mis-information: the GM inline 4-cylinder is a 181 model. This motor does not have a closed system but rather circulates water from stern drive.

 

[Don S]

Re: Water in oil/ Blown exhaust Manifold?- Newbie needs advice

What are you doing, guessing at what you have? What's the model number of your engine. HP rating and cubic inches means nothing if you don't really know.
Model numbers and engine serial numbers. Now there is something you can use.

 

[Reel Poor]

Re: Water in oil/ Blown exhaust Manifold?- Newbie needs advice

It's NOT a 470 because the intake and exhaust are on the same side of the head in his pics.

Looks like a 140 to me.

 

[canuto]

Re: Water in oil/ Blown exhaust Manifold?- Newbie needs advice

It's NOT a 470 because the intake and exhaust are on the same side of the head in his pics.

Looks like a 140 to me.

 

[canuto]

Re: Water in oil/ Blown exhaust Manifold?- Newbie needs advice

It's NOT a 470 because the intake and exhaust are on the same side of the head in his pics.

Looks like a 140 to me.

Thanks for the help in getting the engine ID'd. The engine serial # 4155386 purchased in '75 is only thing in the owner's manual. Is there a website which can narrow it down for me.
Other info provided on manual:
CU in. : 181/( 2967cc)
N of Cyls: 4
Bore: 4.00"
stroke 3.60"
compr ratio 8.5 to 1
This GM motor came with Mercruiser Stern Drives Models 120-140-165 in mid 1970's.
That's about all I know about the engine. I tried googling it without any luck. Thanks for all input...

 

[Reel Poor]

Re: Water in oil/ Blown exhaust Manifold?- Newbie needs advice

It's a 140.

Use your serial # when purchasing parts.

 

[Reel Poor]

Re: Water in oil/ Blown exhaust Manifold?- Newbie needs advice

Since you have the head off take it to a local machine shop and have it checked for surface flatness, cracks, and have the valves checked. With the amount of rust present it will be better checked than left as is.

If the impellor has not been replaced in the last couple of years replace it. If it's chewed up and missing pieces, you need to find all the missing pieces. They can and will restrict water flow. I would also replace the thermostat.

Do you have pics of the intake/exhaust manifold?

With the amount of rust in the intake and exhaust runners I would tent to suspect the manifold.

 

[canuto]

Re: Water in oil/ Blown exhaust Manifold?- Newbie needs advice

Since you have the head off take it to a local machine shop and have it checked for surface flatness, cracks, and have the valves checked. With the amount of rust present it will be better checked than left as is.

If the impellor has not been replaced in the last couple of years replace it. If it's chewed up and missing pieces, you need to find all the missing pieces. They can and will restrict water flow. I would also replace the thermostat.

Do you have pics of the intake/exhaust manifold?

With the amount of rust in the intake and exhaust runners I would tent to suspect the manifold.

Thanks for all the help. Machine shop said all looked good : no cracks or warpage, not a blown head gasket either. I'm leaning toward a possible bad gasket on the exhaust manifold before the riser which might have created leakage into the exhaust manifold.
The exhaust manifold has about 1/4" walls so I became a little sceptical it rusted through so I placed painters tape over the riser outlet and blew into water inlet and got some good back pressure. I'm buying a gasket tomorrow and trying it again before investing on a exhaust manifold but still concentrating on exhaust manifold as primary suspect.


Impeller is next - I will bet you guys are right on that was the primary malfunction which created the overheating,

 

[Bondo]

Re: Water in oil/ Blown exhaust Manifold?- Newbie needs advice

To Test the Exhaust Manifold,..........

Block Off the Water Ports,........ Fill it with Water,.... Then Pressurize it with Air to about 15psi.......
It Should hold Pressure Indefinitely,......
And,.....
By shining a light in thru the various Exhaust Ports,.... You'll be able to See the Leakage,...
If there Is any......

Where the Riser bolts to the Manifold,......... Is it Perfectly Flat,+ Clean,..??..
Or is it Pitted,+ generally Rough,..??...

The exhaust manifold has about 1/4" walls so I became a little sceptical it rusted through

If this motor has been run in Saltwater,..... It's Probably Rusted Thru,...
And,... The flange where the Riser bolts on is Usually the 1st place it Goes........
But Not Always.......

 

[canuto]

Re: Water in oil/ Blown exhaust Manifold?- Newbie needs advice

To Test the Exhaust Manifold,..........

Block Off the Water Ports,........ Fill it with Water,.... Then Pressurize it with Air to about 15psi.......
It Should hold Pressure Indefinitely,......
And,.....
By shining a light in thru the various Exhaust Ports,.... You'll be able to See the Leakage,...
If there Is any......

Where the Riser bolts to the Manifold,......... Is it Perfectly Flat,+ Clean,..??..
Or is it Pitted,+ generally Rough,..??...

The exhaust manifold has about 1/4" walls so I became a little sceptical it rusted through

If this motor has been run in Saltwater,..... It's Probably Rusted Thru,...
And,... The flange where the Riser bolts on is Usually the 1st place it Goes........
But Not Always.......

Ok, blocked off water ports, filled w /H2O and pressurized with 15-20psi. with no visible leaks into exhaust ports. My attention is now on bad gasket on riser elbow attaching to exhaust manifold, area between water jacket and exhaust might have caused gasket to fail( not a lot of gasket separating the two!). the flange does not appear to be pitted or corroded(fresh water use)
Another theory of mine is exhaust manifold gasket might have not been tight and water seeped in between exhaust manifold and head when water was present on top of motor.
I went ahead and had the head-redone for $200. just to be sure. I will begin re-assembly to see if this fixes my problem.
Thanks for all the great advise.

 

[beauff]

Re: Water in oil/ Blown exhaust Manifold?- Newbie needs advice

Let us know the outcome. I would like to know.