Hello. We had our 19.3 Chaparral boat with a 4.3 liter Mercruiser engine winterized by our local marina in Sept 2012. We put it in the water end of June 2013. After only a 20 min. ride, there was a milky white substance over the top of the engine. Another marina diagnosed the issue as a cracked intake manifold, likely due to improper winterization. The boat did not run hot at all. The Marina where we had the boat winterized claims the engine overheated and that's what caused the crack in the manifold. After doing a lot of research with Mercruiser dealers they also claim that's impossible otherwise other parts would have melted as a result. Does anyone have an opinion on whether other factors, other than poor winterization, can cause this type of damage.
Intake Manifold Cracked - Winterization issue?
- Thread starter esnedden
- Start date
If it is only a crack in the manifold, then yes, I think it is bad winterization. If you overheated enough to crack an intake manifold, you would have also most likely blown a head gasket and warped the heads or melted something else as well.
"If it is only a crack in the manifold, then yes, I think it is bad winterization. If you overheated enough to crack an intake manifold, you would have also most likely blown a head gasket and warped the heads or melted something else as well."
This is a follow up question and I have seen this kind of damage reported before, “If you overheated enough to crack an intake manifold, you would have also most likely blown a head gasket and warped the heads or melted something else as well.” Would the over temp alarms come on and warm you to shut down the engine before this catastrophic damage would happen or if the temp alarms come on it’s too late to stop this kind of damage?
Thanks,
Bruce
This is a follow up question and I have seen this kind of damage reported before, “If you overheated enough to crack an intake manifold, you would have also most likely blown a head gasket and warped the heads or melted something else as well.” Would the over temp alarms come on and warm you to shut down the engine before this catastrophic damage would happen or if the temp alarms come on it’s too late to stop this kind of damage?
Thanks,
Bruce
tugboat kevin
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there also prone to freeze cracking the top of the block just under the intake manifold ive been at this a while and have never seen a cracked intake on a 4.3
Like Kev said, intakes rarely crack from over heating cuz the incoming fuel/air mixture is very cold.
Check oil for water contamination. Loose intake bolts can leak water into the block. There's no oil anywhere in the intake but there is oil vapor from the valve covers that can 'foam' from water in the oil and out the crankcase ventilation hose to the carb.
Check oil for water contamination. Loose intake bolts can leak water into the block. There's no oil anywhere in the intake but there is oil vapor from the valve covers that can 'foam' from water in the oil and out the crankcase ventilation hose to the carb.
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I don't know if this applies to your problem, but take a look at this:
http://www.marinemechanic.com/omc/4155.htm
My old '88 pre-Vortec does not have this plug, but some apparently do.....
http://www.marinemechanic.com/omc/4155.htm
My old '88 pre-Vortec does not have this plug, but some apparently do.....
I remember how the "Buick" V6 (we had one in a Century and one in a Cutlass) had IIRC three threaded ports into the water passage in the front of the intake manifold. Various Coolant Temperature Senders. One started the radiator fan, so a boat wouldn't need that one. Aha! A Manifold Drain!