Strange Problem

[olbuddyjack]

Re: Strange Problem

the exhause valve on both the dead cylinders are concave from edge to edge.

Thats known as "sucking a valve" or a "tuliped" valve. The valve will have to be replaced. <br /><br />Its caused by high cylinder temperatures melting the valve. High cylinder temps are usally caused by lugging or from timing. As little as 4 degrees can make a difference. <br /><br />Make sure you cure the problem and not just the symptom.

 

[MNOBLE]

Re: Strange Problem

The heads are in for repair and valve replacement. The tech there said they can also be cause by an extreme lean condition or a vaccume leak. so once all back together i will go through everything with a fine tooth comb. <br /><br />Mike

 

[rbezdon]

Re: Strange Problem

MN, olbuddy is right AND you have signs of overheating earlier in your posts. The damaged valves are cuased by another problem that needs to be fixed or you'll be doing this again, soon.

 

[MNOBLE]

Re: Strange Problem

I dont want to do this again any time soon. What should i look for that i havnt already. I have an audible alarm system that connects to 3 ( i believe ) differently located sending units. it never sounded. I also have never seen the guage go over 140 while running. Does climb over that a bit more after shutting it down. What how much temp increase should i expect, say 5 minutes after shutting it down.

 

[ottawamerc]

Re: Strange Problem

temp rise after you shut down is normal. mine does rise to about 150+. Since the engine is hot and there is no circulating water the temp will increase. It should drop back down to 140 soon after startup.<br /><br />Scott<br /><br />----Whish I had never sold my old boat-------

 

[MNOBLE]

Re: Strange Problem

Update, I got the heads back yesterday afternoon. Got them installed and got her fired up around 10 last night. Fired right up and prrrrd like a kitten. Didnt let her run more than a few minutes to get warm and inspect the valve adjustments. all is well so far. I do agree with you guys, there was / is some sort of serious cooling system failure. a few of the intake bolts and a couple of spots on the intake ( port for the choke mechanism ) looked as if they had been subjected to extreme temp. So, ill ge the valve covers back on this morning, the adjust the carb then let her run for a while. while monitoring the temp closely. Any other ideas?, BTW, the manifold and risers looked great and now have new gaskets. <br />Thanks you all your help everyone. <br /><br />Mike

 

[MNOBLE]

Re: Strange Problem

OK ive gone through everything. and everything appears to be in order. She is running great again. As for the overheat problem, i see nothing wrong. I have a laser temperature probe, using it, with the engine running after about 15 minutes both manifolds, risers and the down y pipes were all the same temp ( about 130 +/- 3 degrees) no hot spots on the manifolds, intake or exhaust. I also hit the sides of the block and it is about 150 degrees throughout. averything apprears to be in order. Taking her out on the lake for the weekend. I will report when i return. THanks again everyone for all your help and suggestions. <br />Mike