170 overheated and now is getting water in oil

nhazzard

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Jun 19, 2011
Messages
8
Hello all,

I just bought this boat last summer. This is my first boat and first time posting. Although, I do read the post quite often and have found you all to be very helpful.

My boat is a 1986 Imperial V192. It has a Merc 170 with a closed cooling system. Overall it treated me very well last year.

When I winterized it last year I made a fatal mistake. I ran the engine for several minutes without using any water for the sterndrive. I did not realize that even though it is a closed system it still needed a raw water source. I did not find out about the damage I had done until a few days ago when I returned the boat to the lake. I completely smoked the impeller in the sterndrive. It took a while for me to discover this. In the mean time, I was troubleshooting other possibilities. Throughout that process I continued to overheat the engine. FYI... I know I am a DA and I don't mind you thinking so. Just don't say it out loud...lol

Well I replaced the impeller, bought a set of muffs, and a garden hose. I tested my work and all seems well. In fact, the motor is running so cold now that I cannot even get the temp gauge to move. Starting to think there may be a problem there too. Maybe a loose wire or bad sending unit. Also, I took out the thermostat and may have placed it in the wrong way?

I just changed the oil before getting the boat back in the water. Up until yesterday, the oil looked nice and clean. I drove the boat today hard for about 15 minutes trying the get the motor up to normal running temp. It never did heat up and the gauge never moved. A few hours later I went back out to clean the fuel filters. When I removed the mechanical fuel pump, I noticed I had water in the oil. I pulled the dip stick to confirm if there was water there. Indeed there was. Not a whole lot, but enough to where the oil needs to be changed again.

I also noticed some bubbles coming from the block to exhaust gasket. They stopped after just a few minutes of running the engine.

So here is my question.

What all could be wrong and where is the best and cheapest place to start?

I am thinking head gasket, intake gasket, or exhaust manifold gasket. Worst case scenario, cracked block or head.

If the head is cracked, is it worth fixing or should it be replaced? How much would a head cost? If the block is cracked can it be sealed with something or is it trashed?
 

nola mike

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Apr 22, 2009
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5,474
Re: 170 overheated and now is getting water in oil

You got a bad hg at a minimum. Get the head checked for warp/cracks. Exhaust bellows/shutters also could have been damaged. Blocks probably ok. Others will chime in I'm sure....
 

nhazzard

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Jun 19, 2011
Messages
8
Re: 170 overheated and now is getting water in oil

You got a bad hg at a minimum. Get the head checked for warp/cracks. Exhaust bellows/shutters also could have been damaged. Blocks probably ok. Others will chime in I'm sure....

I believe I know what you mean my exhaust bellows, but I have no idea what you mean by shutters. Please explain. Thank you.
 

Pete104

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Apr 30, 2011
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Re: 170 overheated and now is getting water in oil

You got a bad hg at a minimum

What's an hg?
 

stonyloam

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Mar 13, 2009
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5,827
Re: 170 overheated and now is getting water in oil

Sounds like you overheated and now have blown the head gasket (hg):facepalm:. I would ordinarily suggest a compression test, however if it is antifreeze in the oil, you need to change it before you run it again. The antifreeze in oil can be very hard on the bearings. You might do a compression test cold, not the best way to do it, but if you have blown the gasket it should show up. If a head gasket you will need the manual to do the job properly. Mercruiser manual #8 is the one you need. Any questions, there are lots of guys here to help. Good luck.
 

Pete104

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Re: 170 overheated and now is getting water in oil

:facepalm::facepalm::facepalm:
 

achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468
Re: 170 overheated and now is getting water in oil

And since you ran the engine (hard) with a dead WPI (Water Pump Impeller) you now have a melted WPC (Water pocket cover) and that will need to be attended to before you put the engine back into service, or you'll get more overheating....

Chris.........
 

nhazzard

Cadet
Joined
Jun 19, 2011
Messages
8
Re: 170 overheated and now is getting water in oil

Sounds like you overheated and now have blown the head gasket (hg):facepalm:. I would ordinarily suggest a compression test, however if it is antifreeze in the oil, you need to change it before you run it again. The antifreeze in oil can be very hard on the bearings. You might do a compression test cold, not the best way to do it, but if you have blown the gasket it should show up. If a head gasket you will need the manual to do the job properly. Mercruiser manual #8 is the one you need. Any questions, there are lots of guys here to help. Good luck.

Fortunately, because of the earlier overheats there was no more antifreeze left. It was just straight water by the time that the water mixed with the oil.

Thanks for the advice.
 

nhazzard

Cadet
Joined
Jun 19, 2011
Messages
8
Re: 170 overheated and now is getting water in oil

And since you ran the engine (hard) with a dead WPI (Water Pump Impeller) you now have a melted WPC (Water pocket cover) and that will need to be attended to before you put the engine back into service, or you'll get more overheating....

Chris.........

Chris,

If by WPC you are talking about the impeller housing, I bought the kit to replace the entire plastic housing. Both upper and lower. If this is not what you meant, please explain further.

Thank you,
Nate


This is all great advice guys. Please keep it coming until I get this right.
 

achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468
Re: 170 overheated and now is getting water in oil

Chris,

If by WPC you are talking about the impeller housing, I bought the kit to replace the entire plastic housing. Both upper and lower. If this is not what you meant, please explain further.

Thank you,
Nate

Nate,

WPC is NOT the impeller housing. It lives up inside the top box (Drive shaft Housing). It's where the copper tube that runs from the impeller housing goes to. When you drop the lower box (Gear housing) off, look up inside, from the bottom. I bet the WPC (made of plastic) is seriously melted. That will allow the gasket to leak, and when that happens the pressure of the exhaust gasses inside that chamber will force their way into the cooling water and reduce the cooling effect of what water can get through. The easiest test for the WPC is to put a section of clear hose in the income water stream (between the transom plate and the engine thermostat housing) and run the boat normally, (it will not show the problem on flushers as there is no exhaust chamber back pressure). If the hose is getting bubbles in, you have a WPC problem....

Chris......
 

nhazzard

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Joined
Jun 19, 2011
Messages
8
Re: 170 overheated and now is getting water in oil

Chris thank you for clearing that up and explaining how to test it. I do know what piece you are referring to. It did appear to be damaged on the outer edges, but it still held the copper tube nice and tight. There are a few reasons why I did not replace it while it was apart.

One, I could not find it at my local Marine store.
Two, I didn't know it was a plastic piece. It appeared to just have carbon built up around it.
Third, I read posts on here where others said that the four bolts normally break. With my luck, I didn't want to risk it.

When I get a chance I will try the test that you suggested.

Thanks again,
Nate
 

Ryanlewis2010

Petty Officer 1st Class
Joined
Oct 4, 2011
Messages
314
Re: 170 overheated and now is getting water in oil

well what i havent heard anyone mention is a melted heat exchanger since it is a closed coiling system im not familar with them but ive been told an over heat can melt them and cause water ingestion. others will chime in hopefully

Ryan
 

stonyloam

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Mar 13, 2009
Messages
5,827
Re: 170 overheated and now is getting water in oil

well what i havent heard anyone mention is a melted heat exchanger since it is a closed coiling system im not familar with them but ive been told an over heat can melt them and cause water ingestion. others will chime in hopefully

Ryan

The heat exchanger can not melt. Only coolant and raw water flow through the exchanger (no exhaust gasses) so it can not get hotter than the overheated coolant, about 212 degrees. The metal exchanger (like your car radiator) will not be damaged by those temperatures. What can be damaged, if there is no raw water flow through the exchanger are the rubber parts in the exhaust system, the shutters and engine exhaust bellows.
 

Ryanlewis2010

Petty Officer 1st Class
Joined
Oct 4, 2011
Messages
314
Re: 170 overheated and now is getting water in oil

like i said i dont have experience in these systems so it was just a thought. lol
 

nhazzard

Cadet
Joined
Jun 19, 2011
Messages
8
Re: 170 overheated and now is getting water in oil

Sounds like you overheated and now have blown the head gasket (hg):facepalm:. I would ordinarily suggest a compression test, however if it is antifreeze in the oil, you need to change it before you run it again. The antifreeze in oil can be very hard on the bearings. You might do a compression test cold, not the best way to do it, but if you have blown the gasket it should show up. If a head gasket you will need the manual to do the job properly. Mercruiser manual #8 is the one you need. Any questions, there are lots of guys here to help. Good luck.

I just rented a compression tester as well as a coolant pressure tester. Could anyone please tell me what is an acceptable range for the cylinder compression? I'll report back later what the readings are.

Thanks,
Nate
 

Bondo

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Apr 17, 2002
Messages
71,133
Re: 170 overheated and now is getting water in oil

I just rented a compression tester as well as a coolant pressure tester. Could anyone please tell me what is an acceptable range for the cylinder compression? I'll report back later what the readings are.

Thanks,
Nate

Ayuh,.... Reasonably even across the board is a good start... over 100, 'n under 200psi...
 

nhazzard

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Joined
Jun 19, 2011
Messages
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Re: 170 overheated and now is getting water in oil

Ayuh,.... Reasonably even across the board is a good start... over 100, 'n under 200psi...

Ok, I just got back from the boat. I ran the compression test...not very good results I'm afraid. #1 30, #2 61, #3 59, #4 58 psi.

The coolant would not hold pressure at all, however I think the tester might not have been sealing all the way either.

I did find a leak in the exhaust manifold around cylinder #4. It also appeared to be leaking between the exhaust manifold and the coolant fill block (lack of better words) that is on top of the manifold.
 

Bondo

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Staff member
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Apr 17, 2002
Messages
71,133
Re: 170 overheated and now is getting water in oil

My boat is a 1986 Imperial V192. It has a Merc 170 with a closed cooling system. Overall it treated me very well last year.

Ok, I just got back from the boat. I ran the compression test...not very good results I'm afraid. #1 30, #2 61, #3 59, #4 58 psi.

The coolant would not hold pressure at all, however I think the tester might not have been sealing all the way either.

I did find a leak in the exhaust manifold around cylinder #4. It also appeared to be leaking between the exhaust manifold and the coolant fill block (lack of better words) that is on top of the manifold.

Ayuh,.... Are ya in Love with the boat,..?? if not, Part it out, 'n take the cash to buy another 1,....

Without a 470 motor.....

Hope yer not to deep into it,...
The hole will be Much Deeper, gettin' it runnin' again...
 

nhazzard

Cadet
Joined
Jun 19, 2011
Messages
8
Re: 170 overheated and now is getting water in oil

Well after a long hard day and another $75 I think I may have solved all of my problems with the overheat and water in the oil. As I mentioned earlier, I pulled the exhaust manifold. I could not buy the correct gaskets that I needed. So I bought a roll of gasket maker. I needed two gaskets. One for the top and one for the side. I made both of those myself and cleaned and resurfaced the faces as much as I could. The seal seems to be okay. I checked the coolant pressure again. It stayed around 15 lbs for almost 20 seconds. Even then it only dropped about 1/2 a lbs. I'll retighten the bolts tomorrow and then it should be fine. I went ahead and replaced the spark plugs while I had it all apart. I still need to change the oil but I ran out of time today. I should have that done by tomorrow. Once I know everything is good, I'll run a good fuel system cleaner through it. Hopefully it will help with the compression at least a little. I think I might buy some really cheap oil to run through and try to clean out that water before I put the good stuff in. Any thoughts on that idea?


Thanks for all the help everyone.
Hopefully, this thread will help someone else.
 
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