Coolant in the oil!!!!

Hey guys posted once before. 1986 Mercruiser 170 Alpha 1. I replace my impeller and thermostat. Motor was running great and was pumping fine. throttled up a little bit after warming her up heard a pop then a few seconds later i saw white oil coming out the oil breather. I shut i down and pulled it apart. The head gasket was on backwards and and it had a small rut in it over the number four cylinder that let the coolant through. Have the head at the machine shop and the gasket kit on the way, should have it back together this weekend. All together quite easy to tear apart.

Re: Coolant in the oil!!!!

I don't think you can put it on backwards, but the book says the word "front" is down, but on mine it was up, but who knows? It is best to use an OEM Mercruiser head gasket for that motor. You might consider hardened exhaust seats while you are having the head worked on. Yeah blown #4, been there. Welcome to the club.

Re: Coolant in the oil!!!!

Yeah "front" was up and over number four not "down" over number one. Got the Sierra kit from IBoats on its way. While I had it apart I also sent the heat exchanger to get cleaned up and am having the starter bushings done. Figured might as well get to that stuff right now.

Re: Coolant in the oil!!!!

The more I think about your problem, the more I am convinced you have serious freeze damage. Probably a block and heat exchanger.
I really don't think your closed cooling system has enough coolant in it to fill the crankcase and overflow milky oil, that takes a constant flow of water. I really don't think the head gasket installed wrong could cause it either.

Re: Coolant in the oil!!!!

If it had antifreeze in it, it doesn't seem too likely that it was freeze damage, unless the antifreeze was really diluted. I have to agree with Don on the head gasket, don't see that much coolant leaking in that way, unless the head is cracked (your machinist can tell you that). Are you sure it is antifreeze, should be able to smell it. There is 11 quarts of coolant, so that is plenty to overflow the crankcase. There is only one thing left that I can think off. If the weep hole in the coolant pump housing was plugged you could have blown the rear camshaft water pump seal and dumped the antifreeze into the crankcase. Need to figure out for sure where the coolant came from. Good luck.

Re: Coolant in the oil!!!!

When I pulled the head I dumped gas down the intake and exhaust ports had seepage thought valve job. Machine shop said i've got a crack in between the intake and exhaust over the number four cylinder. That's why it ran fine at low rpm's but began to pop at higher ones. I believe that it just needed full throttle to finally push the coolant through.

Re: Coolant in the oil!!!!

Looks like it is time for a new head . You can check on e-bay, there is at least one on there that has been rebuilt for what seems a reasonable price. One thing to consider here is that there is no adjustment for valve lash on the 470 rocker arms. The lash is determined by pushrod length. So with a new head you will need to check pushrod length. The procedure is described in Merc manual #8, which you need to get if you do not already have one. The procedure doesn't look too bad, it is gettin your hands on the lifter collapsing tool that appears to be the problem. Look at #5 of this thread to see one: http://forums.iboats.com/showthread.php?t=292942&page=1 . And here is a thread from natemoore http://forums.iboats.com/showthread.php?t=353035&highlight=homemade+tools # 18 shows his homemade tool (he is a wizz at this stuff). Anyway hope things work out OK for you.