1987 Chevrolet 350 tbi high idle

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iamtherealJayy

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1987, 1978, 1976
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Engine Size
350, 350, 350
@Hugomartin if you’ve got blow by sounds like you’ve got excess crankcase pressure for some reason, I’m not 100% sure what causes it but you may want to check your vents (pcv etc) and see how everything is doing, I’ve had to clean my oil breather cap twice because it gets oil on it I just use a little dawn and clean it up and dry it THOROUGHLY and put it back, I don’t have blow by as far as I know but I know a little smoke/steam comes out if I shut the engine off and open the oil cap, but it just kinda leaks out there’s no pressure behind it. And for your radiator hoses if they’re new like mine and you’re still having problems you may ought to replace water pump and maybe clean out the coolant passages while you’ve got the water pump off and no coolant in the system. Maybe just get the water hose out and flush the system a few times to get clear water and a good flow coming out. That’s just an extra precaution I’m going to do while I’ve got mine off to make sure it’s all clean coolant circulating.
 

AuroraGirl

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400(?), 350
From my limited knowledge set the dist cap slightly advanced and goofing around with the idle screw are the only two ways I know of tuning this truck. Mine is still spitting oil out the dipstick I suspect my idle still may be high... but from what I’ve been reading the valve rings? Could be an issue. I get a good amount of blow by on the valve cover where the pvc valve is at. I’m also unsure if my pvc valve is working correctly, it runs fine but pisses out oil
oh god.

Please pay someone to look at yours and stop touching screws. your crankcase is pressurized from either combustion blowby/things escaping into the crankcase or there is a blockage somewhere in the ventilation that allows pressure to both enter and exit the crankcase.
 

AuroraGirl

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Appears to me that there’s two serpentine belts and a v belt? The v belt goes to power steering. I asked dad last night if he ever replaced the water pump and he said he couldn’t remember but it’s a good possibility it’s junk. He said to let it run and check the “weep holes”? And see if the water pump is letting out coolant. He said when it was overheating on him he drained the coolant several times and described the liquid as a brown color(rust?) and after he said that I remembered when I first got it abs drained the coolant to change lower radiator hose it was also an orangish brown color. I’m going to try to get the air out today and if that doesn’t help I’m going to replace the water pump. My ALDL cable came in yesterday so while I’m trying to get air out of the system I’ll leave a laptop hooked up and monitor what’s going on and try to see when closed/open loop occurs and any other changes I think may be useful.
Edit: the alternator is only one I know for sure is serpentine(middle) the air pump belt I honestly can’t remember
your truck appears to have a v belt on the back for PS, a poly v belt for the alternator and water pump, and a.... vbelt... maybe... for the air pump on the front?can you show another angle
 

AuroraGirl

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AuroraGirl

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I think your fan is pointed the right direction for a non-serpentine. I think... i guess it would make me wrong too but it seems to work for my setup.
 

iamtherealJayy

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@AuroraGirl are you calling the flat belt a poly v belt? I thought it was serpentine oops. But the alternator has a flat belt and the other two are probably v belt. I’ll go get another photo or a few
 

iamtherealJayy

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Engine Size
350, 350, 350
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iamtherealJayy

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Here’s a few photos from different angles including the last one is from below
 

AuroraGirl

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@AuroraGirl are you calling the flat belt a poly v belt? I thought it was serpentine oops. But the alternator has a flat belt and the other two are probably v belt. I’ll go get another photo or a few
Poly v belt is what a wide v belt is called. a serpentine belt has a tensioner and the whole system uses that to tension the belt and its constructed very differently. the smooth side of the belt turns the water pump often
 

AuroraGirl

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Here’s a few photos from different angles including the last one is from below
Try turning that fan with your hand.. whats it feel like
 

iamtherealJayy

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Spins as far as I push it, it’s not loose like a bearing per day but it’s not difficult to spin
 

iamtherealJayy

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Also I can’t get tuner pro to recognize my vehicle ive got com all set right it just won’t connect to vehicle
 

iamtherealJayy

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Side note: coolant isn’t bubbling like it was other day
Also coolant hasn’t gone down… rather it has went up and over flowed a bit
 

AuroraGirl

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Unless my part number search is misleading, youre using a serpentine belt on your truck for a 1988 chevy which has a serpentine system.

But i cant be sure, half the companies list their poly belts as also serpentine...
 

AuroraGirl

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400(?), 350
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Side note: coolant isn’t bubbling like it was other day
Also coolant hasn’t gone down… rather it has went up and over flowed a bit
heat expands coolant
 

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