Merc170 I/o over heating

[fisherman85]

I've fished atleast 3 times a week since march find very well. I take the owner of my company this past wed hoping to cruise to 400 fow to start wether I left off the night before. heres what happend started main engine at sandy creek in hamlin get into the lake start picking up speed 10 min later 6o fow temp gage is all the way up stop the boat fast n smoke coming from under motor cover lifted cover coolant mostly on the side wether the reservoir is located because its a closed cooling system there ended up being none left in motor lucky for the 9.9 johnson I wasnt standed anyone have any suggestions on where to start n what it may be started mint as usual really a bad time for motor to act up as fishing is rely picking up please give me some ideals and if anyone is close by spencerport n can take a look out give a hand ill make it worth ur while n may even take u out for a day thanks Rich

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[G-Daddy]

Any sign of coolant in the motor oil?

[fisherman85]

No none oil looks clean and just put muffs on n new coolant no white smoke coming out of prop our anything

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[Wrestling Coach]

The 470 has an aluminum block and an iron Ford 460 head. Two different metals that expand and contract at different rates. These engines DO NOT like to be overheated for that reason. If you pegged the temp gauge and got it that hot the head gasket has almost certainly been damaged. First you have to try to figure out why it got so hot. Impeller in your outdrive bringing lake water in to your heat exchanger or water pump circulating the antifreeze in your closed cooling system that is cooled through the heat exchanger would be the first two places to start. Did a hose on the exchanger or elsewhere burst? Sometimes the impeller fails and pieces will end up in the heat exchanger blocking some of the water flow. Or your heat exchanger could need cleaning much like the radiator of a car. However that should not have brought on sudden high temps but rising over time. In addition you will have to check the head gasket. A compression test can give you information on the condition of the head gasket. You really need a good mechanic familiar with these 470's.

Dennis

[W.W.IV.]

Theres a chance you may have warped the head also. Hope not.

[Wrestling Coach]

Theres a chance you may have warped the head also. Hope not.

Agree. If the head comes off to replace the head gasket definitely send the head out to be checked for cracks and how true it is. Use good gaskets from Mercruiser to put it back together also. The aluminum block is an open deck design and must have a good sealing gasket. Know how to torque and then re-torque the head. Keep all the pushrods in the SAME HOLE when reassembly is done. Valve adjustment is by the length of each pushrod. There is no valve lash adjustment beyond that. Much,much more.

Dennis

[UpGrady]

If there is no coolant remaining in the engine and there was visible coolant in the bilge and none in the oil, then chances are you busted the first seal before the seal to cam shaft. There is a weep hole at the bottom front of the engine behind your belt that will allow a steady stream of coolant to leak out. The enitre front of the engine needs to be lifted out to replace the seal, it is a pretty big jump but it is a fail safe for these engines. That being said, your bigger problem could be the temperature that engine got to, so do be prepared that you may have warped the head and done other damage as well. It might be wise to refill with coolant with the mechanic and ensure that engine appears to be running properly and observe if coolant is coming out of the weep hole I described.

If I misunderstood that you did not see coolant in the bilge area then the only other possibility would be escaping fluid from the exhaust manifold seal.

I have twin470's and have been thru of these issues with my starboard engine. I check all fluids before I even start the engines and leave the dock just to be sure.

There is alot of literature on the internet on both of these issue just do a search.

Bill Zahn- Independent Marine Services in Irondequoit has been doing my work for the past 6 years.