kwoolard
Chief Petty Officer
- Joined
- Feb 9, 2003
- Messages
- 420
Re: Mercruiser 888 overheating
I have been in your shoes for the last year, so I know how you feel. I have the same set up, only I converted mine to center risers. I still have the block off plate between the riser and the manifolds and the three hose style system as the original log style set up. I would do the following if you know that you have a good outdrive pump:<br /><br />While the engine is running at idle check the water flow through the system on both sides:<br /><br />From T-stat housing to the rear of manifold - if flow is bad, you have a restriction in the block, a bad circulating pump, or a restriction in the T-stat housing. If flow is good move on to the next check point.<br /><br />Flow from the manifold - disconnect the line from the front of the manifold. If flow is bad here you have a clogged manifold and it probably needs replacing or a good cleaning. If flow is good move on the next check point.<br /><br />Flow into the riser - disconnect the line feeding the riser. If flow is bad, you have a stuck closed thermostat or a restriction in the T-stat cover. If flow is good move to next check point.<br /><br />Idle relief ports - located on the side of the outdrive near the transom. If flow here is bad you either have a clogged riser or a stuck exhuast flapper. If flow is good you have to look at the engine internally.<br /><br />Do you have water in the cylinders, water in the oil? <br /><br />It seems as if you have checked all the above, so next I would do a compression check. Also, you might want to do a trick that helped me figure out what I think is my problem. I replaced all the water hoses on the cooling system with clear hose, for diagnositic use only. This way you can monitor flow at all points. I would check for air bubbles in the system. Also, make sure you put a clear hoses on the line coming from the outdrive water pump. If you have air, it could be a bad water pump seal, a loose hose connection on the suction side somewhere, or a leaking head gasket.<br /><br />I had air in my system, and pulled the heads. The gaskets were fine but my block was warped 0.018". The shop said they don't believe it was able to seal. <br /><br />Sorry for the long post, but I could talk for days about what I've done and I am down to the last straw.<br /><br />Hope this helps, good luck!! Keep us posted on your progress.
I have been in your shoes for the last year, so I know how you feel. I have the same set up, only I converted mine to center risers. I still have the block off plate between the riser and the manifolds and the three hose style system as the original log style set up. I would do the following if you know that you have a good outdrive pump:<br /><br />While the engine is running at idle check the water flow through the system on both sides:<br /><br />From T-stat housing to the rear of manifold - if flow is bad, you have a restriction in the block, a bad circulating pump, or a restriction in the T-stat housing. If flow is good move on to the next check point.<br /><br />Flow from the manifold - disconnect the line from the front of the manifold. If flow is bad here you have a clogged manifold and it probably needs replacing or a good cleaning. If flow is good move on the next check point.<br /><br />Flow into the riser - disconnect the line feeding the riser. If flow is bad, you have a stuck closed thermostat or a restriction in the T-stat cover. If flow is good move to next check point.<br /><br />Idle relief ports - located on the side of the outdrive near the transom. If flow here is bad you either have a clogged riser or a stuck exhuast flapper. If flow is good you have to look at the engine internally.<br /><br />Do you have water in the cylinders, water in the oil? <br /><br />It seems as if you have checked all the above, so next I would do a compression check. Also, you might want to do a trick that helped me figure out what I think is my problem. I replaced all the water hoses on the cooling system with clear hose, for diagnositic use only. This way you can monitor flow at all points. I would check for air bubbles in the system. Also, make sure you put a clear hoses on the line coming from the outdrive water pump. If you have air, it could be a bad water pump seal, a loose hose connection on the suction side somewhere, or a leaking head gasket.<br /><br />I had air in my system, and pulled the heads. The gaskets were fine but my block was warped 0.018". The shop said they don't believe it was able to seal. <br /><br />Sorry for the long post, but I could talk for days about what I've done and I am down to the last straw.<br /><br />Hope this helps, good luck!! Keep us posted on your progress.