Hey all. Got a 87 Jimmy Sierra Classic with the 350 we bought in the spring. Havent driven it a lot due to a problem with the cooling if any one could give a few ideas would be appreciated. To start the thermostat had been replaced along with the fan clutch( or so I've been told). At an idle she never over heats but you go 5 miles down the road and she will start to get hot pretty darn quick. Last time she got out hot the upper and lower hose were reading about 190ish on my radar with the radiator underneath the pressure cap was around 220. Neither of the hoses are getting sucked in and there are no leaks so I think the cap is doing it's job. There is no antifreeze on the dipstick and it doesn't smell like antifreeze either. We also used a combustion leak test and found no problems. The water pump seems to be working because with the pressure cap off you can see water getting sucked down into the radiator when you step on the throttle. The fluid is disgusting looks like pong scum. We are going to change that. The only thing we have noticed is the large amount of air the fan is pushing out the front. Under the hood there is minimal airflow getting pushed into the engine bay. With my 94 k1500 you can feel and see the air move very well a small rag. Is it possible someone put a pusher fan on? The fan rotate counter close wise if you looking at it from the driver side fender. Any help or advice would be greatly appreciated. Thanks
CK5
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Cooling issue
- Thread starter 87jimny
- Start date
Couple things. The fan should not be pushing air out the front.
What style fan belt do have?
A single serpentine? Or 1-3 V belts? Possibly 1 V belt and flat serp?
Second what temp is the thermostat? Unless your truck is TBI 195° is probably to high. 180° would be good, might even be best even if TBI.
Yes you should do a full system flush. If your cooling system has multiple metals,iron, brass, aluminium, etc use Dexcool. Mix 50/50 with distilled water.
What style fan belt do have?
A single serpentine? Or 1-3 V belts? Possibly 1 V belt and flat serp?
Second what temp is the thermostat? Unless your truck is TBI 195° is probably to high. 180° would be good, might even be best even if TBI.
Yes you should do a full system flush. If your cooling system has multiple metals,iron, brass, aluminium, etc use Dexcool. Mix 50/50 with distilled water.
It could be someone put a fan from a later generation the spins backwards and it is pushing instead of pulling.
A picture of the fan would help us verify the direction of the fan from the angle of the blades
Yep so you need a clock wise fan and fan clutch. Clockwise looking at engine from front. They both should have arrows indicating proper direction.
You can also tell from the direction of the angle of the pitch.
Well the engine rotates clockwise, so if you have V-belts to the waterpump, it also rotates clockwise. The pitch of the fan blades should have the leading edge towards the radiator and the trailing edge towards the clutch.
Do you have a fan shroud? Any idea what water pump was put in it or what clutch it has? There are some designed to go counter-clockwise, but typically the mounting features for accessories is different.
Do you have a fan shroud? Any idea what water pump was put in it or what clutch it has? There are some designed to go counter-clockwise, but typically the mounting features for accessories is different.
That truck i believe has the serpentine belt but the A/C has the v belt
No the serp belt installs and adjust just like a V belt, IF it has a separate belt to drive other accessories, this Clockwise. The Serpentine Counter clockwise is single belt driving all accessories.
Sounded to me like the water pump is correct rotation, with level dropping in Rad as rpm are increased.
Yeah, I think 87-89 were that transition, my 89 had thatOK, I'll stop now, as I don't know anything about this goofy transition setup.
Im trying to figure out how to load a pic of the fan blade now. It definitely does not push any large amount of air into the engine bay. Standing in front of the engine everything rotates clockwise. The serp drives the alt water pump. The v belt drives the ac and power steering. If any can tell me how to load a pic (I'm a dummy when it comes to this stuff).Standing on the outside you can feel a large amount of air getting pushed out front. My 94 k1500 fan will blow your hat off at an idle standing next to the fender. This thing barely moves anything in the engine bay
You have to be a member/minimum number of posts to upload pics.
Is your fan angled this way?
Keep in mind that the belt driving the alternator is called a “multi-groove belt” and not a “serpentine belt” - a serpentine belt wraps around various pulleys on both contact sides and a multi-groove belt acts the same as a conventional “V-belt” with only the one side making contact with the pulleys.
Just stating this because, as said by others, GM started using both setups with the introduction of the GMT400’s ( which actually started in 1987 as early 1988 models ).
Your ‘87 should use a combo of V-belts and a single multi-groove Alt belt with a standard rotation W/P and fan - I’m betting on you got the wrong fan pitch as your problem.
Just stating this because, as said by others, GM started using both setups with the introduction of the GMT400’s ( which actually started in 1987 as early 1988 models ).
Your ‘87 should use a combo of V-belts and a single multi-groove Alt belt with a standard rotation W/P and fan - I’m betting on you got the wrong fan pitch as your problem.
That’s what I’m thinking. If his fan looks like that, it’s wrong.
