It seems like when I come to this forum for advice I always launch into a long-winded story. Here I go again.

I began seeing my temp gauge in my 1993 LT1, C4, running high last summer. It comes down when I use the heater to activate the electric fans so it was manageable.

I was losing coolant gradually after that. I never pressure tested the system because I don't have a pressure tester (poor excuse).

The coolant leak recently got worse. I found it was coming from the weep hole at the bottom of the water pump so I pulled the old pump and sure enough, the bearings were dry and noisy. I put a new pump in carefully and it started fine minus the noise of dry pump bearings.

I put radiator flush in with water and drove it for about an hour. The temp went right back up but once again, I could get it down almost immediately with the heater.

I was thinking air in the system but when I opened the two bleeders, there was no air.

Also I have noticed in the past a stream of water coming from one of the lines that leads into the upper expansion tank. There is no stream of water now. Wouldn't there be a stream if the pump was working?

So I start thinking, is there some way to mess up the spline on the shaft that drives the water pump during installation? I was very careful because I didnt want the gaskets to become misaligned. The spline only lines up one way. So because I have all 6 bolts in and tight, it can't be outside the hole. I seem to remember reading something about a possible point of failure in the drive mechanism inside the cover but I think the opti would be off if that wasn't working.

Any ideas?

 

Well how hot is the hot your talking about ?? Its not unusual for my car to get to 230 in traffic.

I'm guessing your w/pump is spinning just fine. If it wasn't then the engine would boil over inside just a few minutes of driving ....

 

You should have pulled the radiator and cleaned it while you had it down. They are big vacuum cleaners. Take the top shroud off and look inbetween the 6 7mm screws in the front are a pita I used a flat ratchet wrench and el tape on some of them. Clean the fins real good.

My 94 never hits over 228 now.

You did put sealant on the water pump bolts?

 

start it, let it come up to temp, shut off engine, allow to cool, open bleed screw, open radiator cap, add coolant; repeat; in my case I did this four or five times before I got all the air purged from the system.

 

What temperature is it getting to? Your idea of HOT and the power train engineers at G.M. are likely VERY different. What is hot to you?

 

I have never really looked at the radiator or the AC radiator but it makes perfect sense that there would be stuff in there. It spends years sucking tons of air from street level...lots of dirt.

My instinct is to try to clean it as easily as possible. Any opinions on pulling back the plastic shroud, putting the garden hose down in the space and blasting the garden hose from the engine side toward the nose? I would probably try to loosen it up with water then follow with compressed air. I don't see the hose stream bending the radiator coil fins but I"ve never done this before so I don't know for sure.

 

I'm just looking at the gauge on the dashboard. before the electric fan kicks on the gauge goes up to above the half way mark and quickly goes up to around 3/4 and gets almost all the way up to the top mark. I could use my laser temp gauge on the radiator and block. What should the range be?

 

No sealant on the threaded end of the bolts. I put sealant on the block side of the gaskets and snugged the bolts. I don't see any coolant getting out through the bolts.

 

Go by the digital temp analog lies. Best to pull and clean the rad if you go blasting water you can kill your opti. You should use sealer on the water pump bolt threads. On my 94 the fans come on at 228 and 238 or when the ac or defrost is on. If your hitting around 250 you risk your head and gasket.