Closed loop coolant leak in a1985 mercruiser 170

[Provincetown boater]

HI,
I just got my 1985 mercruiser 170 running for the season. Toward the end of last year I kept having to add coolant almost every trip. So after running the engine for about 45 min I shut it down and started searching for leaks. I found a tiny pool of coolant in the front under the water pump cover. Aha I said let me see if these bolts need to be tightened. Bad move After just an eighth of a turn coolant started to really leak bad, I backed the bolt off and the leak backed off.
Ran the engine again and I do seem to be getting a drip.
Do I need to replace the gasket? or is it normally not supposed to be to tight?
Thanks

Pete

 

[Eric 3.7LX Alpha 1]

Re: Closed loop coolant leak in a1985 mercruiser 170

Read this:
http://www.sterndrives.com/470information/470coolantleakrepair.html

 

[Provincetown boater]

Re: Closed loop coolant leak in a1985 mercruiser 170

Read this:
http://www.sterndrives.com/470information/470coolantleakrepair.html

Wow are you kidding me? This is a 27 year old boat and engine. From the sounds of it this repair will cost twice the value of the boat. lol Any other ideas?

 

[Provincetown boater]

Re: Closed loop coolant leak in a1985 mercruiser 170

Wow are you kidding me? This is a 27 year old boat and engine. From the sounds of it this repair will cost twice the value of the boat. lol Any other ideas?

I understand the premise that if these internal seals are leaking my engine is doomed. But what I saw and what I am experiencing is a leak from multiple locations around the seam of the water pump cover. and that when I tried to tighten the bolts it made the leak much worse, then when I backed the bolts off the leak went back to a slight drip. After sleeping on it I still think I have an issue with the cover or it's seal?

 

[Eric 3.7LX Alpha 1]

Re: Closed loop coolant leak in a1985 mercruiser 170

In that link there is a thumbnail photo that can enlarge if you click on it. The front half of the timing cover has coolant, the back half has oil and the timing chain, camshaft. The two seals are pressed into that timing cover.

If they go... you should see the drip out of the coolant "drip passage" as noted on that photo. The front has a gasket (#8 in that photo) that could be your leak. If so, easy fix.

http://www.iboats.com/Timing-Chain-...6818917--session_id.485910906--view_id.174884
or
http://bpi.ebasicpower.com/pc/VICGS33258/MER37ENG

 

[stonyloam]

Re: Closed loop coolant leak in a1985 mercruiser 170

Wow are you kidding me? This is a 27 year old boat and engine. From the sounds of it this repair will cost twice the value of the boat. lol Any other ideas?

Not even close, it will cost less than $100 if you DIY. Thing is, if it is the cover gasket the cure is almost the same, you have to pull the rotor and remove the cover to replace the gasket. If you do that you might as well go ahead and replace the cam seals, and crankshaft oil seal. Last time I pulled my rotor I borrowed a harmonic balancer puller from autozone, worked fine except had to make a spacer to put it back on because it is so deep. Be very careful when you tighten and loosen the bolts on the cover, the cast aluminum is easy to crack. It is not nearly as bad as it reads, and you probably will not have to touch the motor mount. Lots of guys to help here if you decide to do it.