I was supposed to dyno the car today. The dyno is in houston and I went for a roadtrip yesterday to make sure the car was ready and I guess I now know the answer. I had driven about 40 miles just crusing and the temp just skyrockets. Then it comes back down just as fast. I turn around to head back home and it does it several more times on the way back. Each time I put it in netrual and coast for a few secs until it comes back down.

The motor started misfiring on several cyls. I got it back home and found one plug that was solid black and another (on the opposite bank) that appears to have water on it. I turned it over and did not see anything come out of either hole. I am going to put new plugs in those holes and see what happens (maybe run a compression test).

All rockers look good, no water in oil, no water out of the tail pipe.
Yep, its a mechanical temp gauge

No dynojet for the 400 anytime soon

Oh well, gigem aggies. Beat the he** out of OU.

[This message has been edited by jcb999 (edited November 11, 2000).]

 

Given that you have a mechanical and finding water on your plugs, it suggests a gasket or head problem.

Best of luck to you. Hope it turns out to be something minor.

 

If it is a 400 small block I have a good idea. I had the same problem several years back. what i had done was ordered a set of head gaskets that were the thickness i needed but failed to state it was a street motor so the gaskets I got didn't have steam holes. so what happens is the steam holes are blocked off causing steam pockets in the block and head causing very erratic temp readings. one second it would be on 180 the next it would be 240 and back just as fast .hope I might of helped.

 

The head gaskets I used were for a street 400. They had steam holes and everything.

I ran a compression test and I had 200 on all the cyls on the passengerside and
180-175-120-170 on the cyls on the drivers side

I pulled the drivers side head and sure enough, there was water in hole 5. I have not decided what I am going to do yet.