Worse than I thought!

[JSMoore]

The Setup:
1987 OMC Cobra 4.3
Closed cooling system
Compression Checks in the 170's - all cylinders
Cooling system pressure check - holds 14lb. for 2+ hours.
No leaks in exhaust manifolds

A while back, I opened a thread where I indicated that I had some water in the oil and thought that it might possibly have something to do with the intake manifold gasket. Well, I opened her up to see what I have in there. Oh My! This doesn't look good.....

The intake gasket was in pretty sorry condition, and was virtually destroyed when I removed the manifold. Except for all the spilled milkshake, the inside of the lifter valley is very clean. There are a few traces of NEW rust inside there. But, nothing old. There is, however, a lot of rust on the bottom of the intake manifold, under the carb/choke area.

About the only thing that really seems to stick out is that most of the thick, cheesy, milkshake oil is stuck underneath the intake manifold and in the lifter valley toward the back of the engine.

Please take a look at the pictures and throw some advice at me. I really can't afford to replace the engine right now. But, if that's what it takes, that's what it takes.
Thanks!
JSMoore

 

[mkast]

Re: Worse than I thought!

What temperature does this engine run at after thirty minutes of operation?

 

[Dakota47]

Re: Worse than I thought!

Ayuh,... put a Edlebrock aluminum intake and a 1409 carb..

 

[adeneo]

Re: Worse than I thought!

If it looks like that under the intake, and you have been running it like that, it probably looks like that in the oil galleries, oil pan and lots of other hard to get to places aswell.
With determination and lots and lots of cleaning solvent anything can be cleaned, but me thinks it's time to tear it down for a proper cleaning, and probably easier!

 

[jfalco]

Re: Worse than I thought!

clean as much as you can and repair whatever the problem was and install new oil and filter and run engine and if its water and not antifreeze it will evaporate in no time and your oil will be water free.

 

[JSMoore]

Re: Worse than I thought!

What temperature does this engine run at after thirty minutes of operation?

When first started, temp gauge goes up to around 180*, then drops almost immediately to around 160*. It has a 160* thermostat in it. Temp stays around 160* for as long as you run it.

The conditions you see here in these pictures happened suddenly. I check the oil EVERY TIME I use it. There is no history of oil contamination. I discovered the contamination when I started the motor on the muffs during my winterization routine. It's not like this happened over a long period of time. And, the inside of the engine shows that. There's almost no rust or corrosion on any of the parts except that shield on the bottom of the intake.

 

[John_S]

Re: Worse than I thought!

What do the inside of the valve covers look like?

Rust on heat shield of intake, is about the same as what I've seen on a number of sbc. That is nothing to worry about.

Lots of black wet carbon on exhaust crossover. Does your exhaust passages look the same? Looks like it has been running very rich?

If it was holding pressure, how did you narrow it to the intake?

 

[JSMoore]

Re: Worse than I thought!

What do the inside of the valve covers look like?

Rust on heat shield of intake, is about the same as what I've seen on a number of sbc. That is nothing to worry about.

Lots of black wet carbon on exhaust crossover. Does your exhaust passages look the same? Looks like it has been running very rich?

If it was holding pressure, how did you narrow it to the intake?

Exhaust ports, and the exhaust passages inside the exhaust manifold are dry, and black in color. The spark plugs are dry and black, as well. So, yes.... it is running quite rich. The exhaust crossover on the intake and at the crossover ports on the heads ARE a little wet.

My initial impression that the problem may be with the intake was based on my experience with a Chevy S-10 4.3 of the same era. The early 4.3 intake gaskets had a habit of failing around the front coolant crossover. And depending on how bad the failure, could be barely noticeable - or very evident. My S-10 failed that way and I had to replace the intake gasket.

One of the last "external" things I did, before opening it up, was to do a leak-down test on the cooling system. When I saw that it held pressure well, I knew the coolant system was not the culprit. So, I am looking at other things, as well. At this point, I'm really at a loss.
JSM

 

[wallerus]

Re: Worse than I thought!

2 things.
You could very possibly have a leak at the intake gasket. Cleaning the surfaces and installing a new gasket will solve that problem.

You could have a leak at the back of the intake causing the engine to suck moisture in while running. Think of a little milk in the oil cap.

I would clean all the milk off of it. Pull the heat shield off the bottom and clean that area. Try not to wash it into the oil pan.

Running to rich will cause the crank case to have unburned fuel in it. The fuel will condense and get water with it.

Run the engine with some crank case cleaner in it and change the oil and filter.

This engine should have a 180 degree tstat in it.

 

[JSMoore]

Re: Worse than I thought!

I think I may have had a EUREKA!!! moment! I'm almost positive I've found the source of my water contamination!

I spent a couple of hours cleaning up the mess this afternoon in preparation for putting everything back together. The inside of the motor is now clean as a whistle. All reachable signs of water contamination are GONE!

I completed the day by laying out all of my new gaskets just to make sure all were accounted for. Included with the intake manifold gasket set was the gasket for the base of the distributor. !!!EUREKA!!! It hit me that when I pulled the top of the motor apart, THERE WAS NO GASKET BETWEEN DISTRIBUTOR AND MANIFOLD! It was probably left off during some maintenance before I ever bought the boat. (Please understand that this is my first year with this boat and my first I/O.)

As part of my winterization routine, I gave the motor a good wash down with a moderate pressure water hose. Most of the "cheese" inside the motor was collected around the distributor shaft and the back of the lifter valley. So, I'm going to go out on a limb here and say that when I washed the motor, the lack of a gasket between distributor and manifold allowed enough water to get into the lifter valley to cause the contamination.

So.... This thing is going back together with new gaskets and get run the way she is, (after a couple of good oil changes!).

Thanks to those that took the time to read all this and make some really good suggestions!
Cheers!
JSM

 

[wallerus]

Re: Worse than I thought!

Good catch and good luck. Let us know how it comes out.