87 chev running hot

[Al_Brokenwing]

I have a 1987 silverado with a 305 fuel injected. It's been running hot lately. I changed the water pump not too long ago and was wondering if I might have the wrong one. Were there two different pumps in 87? If not do you have any other ideas whats causing the problem.

[xtreme80]

start with the basics first. does it have enough coolant in it? If not, why not? Has it been low for a while, or is it leaking? Next I would try a new thermostat. For 15 bucks you can be sure you have the right one in there. Its possible that the one you ahve in there now is set for a higher temp, and might not be opening soon enough.

Start with the basics man, and go from there.

[Al_Brokenwing]

The coolant level is good. As for the thermo stat right now i have taken it right out to see if it was causing the problem. Still no change.

[Slonaker]

Originally Posted by Al_Brokenwing

The coolant level is good. As for the thermo stat right now i have taken it right out to see if it was causing the problem. Still no change.

I would get a quality thermostat and put it in. It may help.

Did you overheat it before you replaced the waterpump? You might have cracked a head or blown a head gasket if you did.

An acquaintance told me last weekend that he replaced a smallblock waterpump with one from Auto Zone several years ago, and it had no impeller. He said that was the last part he bought from them...

Slonaker

[Al_Brokenwing]

I don't think the thermostat is the problem, seeing as after I removed it the truck still ran hot. I still think I may have the wrong waterpump because many things were different on the EFI motor. One thing that was different was the wide accessory belt. I don't know if I'm headed the wrong direction but all suggestions are welcome. If we bounce around enough ideas we should stumble upon the answer.

[f.monroe]

An 87 should have a standard rotation waterpump and in 88 they went to a reverse rotation pump . I think it is reverse rotation with the serpentine belt setup . I Think this is how I remember it . The parts books arent always straight on 87s since they were a little of both . Check the part number they sold you against a pump for an 88 or even 90 truck and then check it against a pump for an 86 . It should be the same as the 86 . Something to look for . Frank

[piecesparts]

My bet is on the wrong type of water pump. they look the same, but run different. Follow what f.monroe said and I bet you are going to be surprised.

[smills78gmc]

I have a 78 that I did a serpentine conversion on. I have the reverse rotation water pump. BUt I used my old fan setup, except the clutch. Today was the first day I drove it, It got pretty warm but didnt overheat. I took the fan off and switched its direction. Hopefully this does the trick. I feel like the biggest dumbass for not thinking about it. I could have f***ed up my new crate motor.

[Al_Brokenwing]

Thanks guys. I will check the part number tomorrow. The thing I'm still not sure of is if the waterpump should be 86 style or 88 style. Does anyone have a fuel injected 87 305 that we can cross check this with? Parts books have been wrong too many times with this truck for me to trust them.

[f.monroe]

Should be like the 86 .Frank

[piecesparts]

You can look at your fan blades and figure out the direction of rotation that your unit needs to turn. Then look at a truck that has a standard set of belts and compare the fan blades. At this point, hopefully, you could see what the difference in the two really is.

[Al_Brokenwing]

the fan blades are the same on my 87 as they are on my 85. The fans are also rotating the same direction. So the waterpump seems to be correct. Now what do you guys think?

[piecesparts]

STILL Do you have the right water pump for your application? Normal rotation or reverse. Do you have the ticket to check the part number?

How long ago did you change the water pump, as you stated above. Is there a possibility that you have a plugged radiator core and now that the weather is starting to warm up, the system is not working well?

Is your timing set to low, that can make a motor run hot?

[Curly86]

Does it have the clutch fan setup
on it? If it does you may have to get the heavy duty clutch fan i had to do that on my 86 that I put a 400 in and it don't run hot anymore