mercruiser 470 help

Hello to all, I am a first time poster in this forum I have been a member for two years now, I have read a ton on here and have gained a wealth of knowledge from all of your advice and help given to others. So Thanks for all your help. If I posted this incorrectly please let me know. I have a 1989 celebrity 190 bow rider with the 470. I traded a couple jet skis for it some time ago. I have replaced a full floor, an engine mount and all interior, I started my project when I spun a rod bearing.
I had all machine work done and with the help of this site learning all the qwerks did a full rebuild. I know this motor in and out. But now after only 1 summer of use I am starting to get coolant in the oil, and some coolant burning off on start up, cam has had speedy sleeves installed on rebuild and new seals and gaskets thru out the motor. My compression readings from the front of the boat to the rear are as follows front cyl. 135 psi mid front 157 psi mid rear 160 psi and rear 120 psi.
I am not getting air bubbles in my coolant reservoir, and I do go thru coolant but only a reservoir full in 4 hrs of running. (I noticed it in the oil after this and quit running it) Is this a head gasket? or could it be something else? I re torqued the head after the first heat up but misunderstood my manual and let it cool, Now Ive learned to re torque when motor is at operating temp. I dont want to wrench anything until Ive gotten plenty of advice from the pros on here, I am going to get the pressure test kit from autozone for the cooling system But cant do it till next week. Please help, I love my boat, and Ive grown fond of this 470 just cause its different and people dont like them. I also did an alternator upgrade at rebuild that Cost me about 15 dollars for the mounting hardware, and a stainless bolt, Plus a little time on the lathe at work.

Re: mercruiser 470 help

If your cam seals are not leaking (nothing coming out of the weep hole) about the only way to get antifreeze in the oil that I can think of is a bad head gasket. You can get antifreeze in the cylinders through a leaky exhaust elbow gasket. Did you use a OEM Mercruiser head gasket? They were designed specifically for the 470 and seal better than aftermaket head gaskets which are auto gaskets. If you have antifreeze in the oil, change it before you start it again as it will trash the bearings in a hurry. Your #1 and #4 compression readings were pretty low, could indicate a HG problem. Good luck.

Re: mercruiser 470 help

The cam seals are not leaking, I ordered my gasket kit from wulffemarine, pretty sure it was sierra parts, are these no good? Ill be sure to get an oem head gasket this time, I was just reading the importance of that earlier today.

Re: mercruiser 470 help

Sierra gaskets are OK, except I would use OEM head gaskets, and exhaust elbow gasket. Some guys run the 470 engines in hot rods and they say that the mercruiser OEM head gaskets hold up much better.

Re: mercruiser 470 help

I drained my oil this morning, and figured the bottom of the pan would be water, it wasn't, but when I pulled the dipstick Saturday out on the water it looked a milky color, so could I have a leak somewhere else other than a head gasket that is allowing coolant into the cylinder and its leaking past the rings and into the oil after I shut down? I see no white smoke while its running other than at start up, just thought if it was a head gasket I would see more coolant in the oil or bubbles in the reservoir, or more white smoke, or even poor performance of some kind.

Re: mercruiser 470 help

Sounds like coolant is going somewhere, a whole reservoir full into the oil would really obvious. You might be losing some out the exhaust if your elbow gasket is not sealing correctly. Is your hose to the expansion tank in good condition?

Re: mercruiser 470 help

The hose is brand new, remember I am getting a sweet smell and white smoke on start up and re start after hot. so I am burning the coolant off, I will pressure test the cooling system and see if its the exhaust manifold, intake, or the head gasket, hopefully its simple.

Re: mercruiser 470 help

Pull the plugs and look at the porcelain insulators around the electrode. Normally they will be tan or brown, if they are white that is an indication the are being "steam cleaned" by coolant leaking into the cylinder. When I did mine #4 plug was snow white.

Re: mercruiser 470 help

stonyloam said:

Pull the plugs and look at the porcelain insulators around the electrode. Normally they will be tan or brown, if they are white that is an indication the are being "steam cleaned" by coolant leaking into the cylinder. When I did mine #4 plug was snow white.

Click to expand...

Yes, mine too. #4 was sparkling clean.
Also after sitting on hook for a couple hours then re-start, motor was hard to turn over while trying to force the coolant out of cylinder, then came the puff of white smoke and antifreeze smell. I'm not sure if you had that symptom also....

Re: mercruiser 470 help

I have never had a hard restart after sitting for a long period, I did once while tubing tho, I gassed it in reverse to stop the boat when i got closer to my fallen tuber, then immediately shut it down without thinking, and i flooded it real good, took about 10 min. before i could restart it again. So after draining and catching most of my oil in a clear jug, Im going to say I had no coolant in my oil, If any just a touch, I see no milkiness to it after sitting in the jug for 24 hrs. I pulled the filter and drained that watching everything drip come out of it and it all looks like beautiful oil. So I am going to safely say I am just burning the coolant, now to figure out how its getting into the cylinder, three out of the 4 plugs are relatively clean on the porcelain Ill post pictures of them, So maybe I am burning it on all 4. Pictures may not be the best but its The best I could get with my phone. the left one is the front of the boat the right is the rear, the first 3 pictures are of 1 side of the plug, the last 2 pictures are the other side of the plug

Re: mercruiser 470 help

Those plugs look good. If you had a significant amount of antifreeze leaking into the cylinder the porcelain would be snow white. I suspect that you may have some leakage at the exhaust elbow/reservoir gasket. You would wind up with some antifreeze in the exhaust manifold that would burn off on startup, and would get some leakage into the exhaust when the pressure in the cooling system begins to build up. It might be worthwhile to pull the exhaust elbow and replace the gasket with a OEM Mercruiser gasket (assuming you have an aluminum manifold) http://www.mercruiserparts.com/showSpecialPicture.asp?pn=18272 Check the surfaces to make sure that they are clean an flat.