Cooling help

[firemedicsafd]

I have an 88' blazer with cooling issues. It will work fine most the time. But sometimes ( a couple of times during a 15 mile trip)it will just increase to 250+ at any time. idle or highway speeds. I have a new thermostat, new SS hoses, electric fans. The only thing i can think of is the rotation of the water pump. I built a serpentine belt system out of an s-10 and bolted it onto a 79 block. i got the water pump for an 88' blazer and mounted the pulley to it. All without problems. Which way does the s-10 water pump turn? And wihch way does the blazer water pump turn? The problem i had before was she would heat up to 250+ and then drop back down and cool fine. I found out that was the thermostat flipped upside down. since i fixed that...i have had this issue. Thanks for the help!

 

[lectric80]

I can tell you it wouldn't drop back down if the pump wasn't rotating correctly. The stock 88 should have had a serpentine system on it, IIRC. That should have been a serpentine belt year, but I could be wrong.

First: Are you judging temp based on the factory gauge? If so it may be reading higher than the actual temperature of the engine.

Second: You say you have a new thermostat, but have you boiled it to verify it is opening correctly? It may just be sticking a little, causing a slight increase in temperature before it releases and cools the engine back down. I have had a few different vehicles that would do this, and after about 2 or 3 cycles of this, it would then balance out and stay normal. I replaced the thermostat on one three times before I got one that would open smoothly at the correct temperature.

 

[Big Blzn]

Or, take out the t'stat entirely just to see what the temp does and go from there.

 

[One_Ton_k5]

I think the serpentine systems require a reverse rotation water pump IIRC.

If it had v-belts, and you went to serpentine that may very well be the problem.

Someone who knows for sure can tell you more.

Just FYI, I went to the NAPA website and looked up your truck, it shows a reverse rotation pump is standard. So just make sure you have the reverse rotation pump.