Who's got the brains to figure this one

[savage8190]

Hi everyone. I have a 1990 gmc jimmy sittin in my garage and Im a little tired of seein it not move. It has a 4.3l tbi engine which i recently swapped into it. The thing runs pretty good but I have come across three problems that just boggle the mind.
1) I have a mysterious coolant theif running loose. I lose coolant pretty fast from the reserve, but not quite as fast from the rad it seems, and there is not a leak to be found. Theres no coolant in the oil, no smoke from the pipe, and no drips on the ground. Hmmmm...
2) It idles fast. It doesnt idle too too fast, it sits at about 1250. But that is about 500 too high. Seems to be fine in gear, and it even drops a bit sometimes if i drop it from park to drive then back to park, but only sometimes, and the drop is very little. I have no vac leaks, ive replaced the tbi gaskets, most sensors are new, and theres no bad wiring. The only abnormality i could find is that the iac is staying extended (not letting air in). I tried replacing it but the new one did the same thing.
3)And the final problem is a weird one. The vehicle has been sitting for about 8 months, and when I took it out for a little spin this problem appeared. There is a grinding noise(like a muffler dragging on pavement) coming from the rear end. Obviously I looked and there's nothing dragging, so I found this noise odd.

If someone could please, PLEASE help me it would me much appreciated. Im a student and I really cant afford to take this thing into the shop for diagnoses AGAIN, (thats right ive had two mechanics look at it and they couldnt tell me squat, although one was my drunk uncle and the other was a canadian tire flunkie) but ive gotta get this thing workin properly ASAP.

[BlazerLT]

Originally Posted by savage8190

Hi everyone. I have a 1990 gmc jimmy sittin in my garage and Im a little tired of seein it not move. It has a 4.3l tbi engine which i recently swapped into it. The thing runs pretty good but I have come across three problems that just boggle the mind.
1) I have a mysterious coolant theif running loose. I lose coolant pretty fast from the reserve, but not quite as fast from the rad it seems, and there is not a leak to be found. Theres no coolant in the oil, no smoke from the pipe, and no drips on the ground. Hmmmm...
2) It idles fast. It doesnt idle too too fast, it sits at about 1250. But that is about 500 too high. Seems to be fine in gear, and it even drops a bit sometimes if i drop it from park to drive then back to park, but only sometimes, and the drop is very little. I have no vac leaks, ive replaced the tbi gaskets, most sensors are new, and theres no bad wiring. The only abnormality i could find is that the iac is staying extended (not letting air in). I tried replacing it but the new one did the same thing.
3)And the final problem is a weird one. The vehicle has been sitting for about 8 months, and when I took it out for a little spin this problem appeared. There is a grinding noise(like a muffler dragging on pavement) coming from the rear end. Obviously I looked and there's nothing dragging, so I found this noise odd.

If someone could please, PLEASE help me it would me much appreciated. Im a student and I really cant afford to take this thing into the shop for diagnoses AGAIN, (thats right ive had two mechanics look at it and they couldnt tell me squat, although one was my drunk uncle and the other was a canadian tire flunkie) but ive gotta get this thing workin properly ASAP.

Ok, the coolant problem. How much goes missing over what time frame?

1250 for idle is really high, it should be around the 500-700 range. I would check for a vacuum leak somewhere. Check all the vacuum hoses and also check the engine timing with the timing wire disconnected. Advanced timing will cause the engine to have a higher than normal idle also.

The grinding noise could be a muffler which is worn out and the interior of it is loose. Also could be the cat. Get under both of them and smack them with the flat palm of your hand and listen for rattling.

Oh, and Crappy tire, don't get me started on those rip off assholes, I don't trust them to do anything. I go in for a tire rotation and they are telling me my brand new shocks are blown. They were 3 days old.

Boy did I ever rip them a new asshole over that one.

[moose 1132]

Not sure about the coolant problem. Fast idle could be out of timing or a bad Throttle Position Sensor (TPS). but most likely sounds like timing. The noise from the rear end- is it when you are moving or sitting still idling? moving- you say it sat for eight months probably rusty brake drums.

[savage8190]

OK as for the coolant i would say that I have to refill the overflow like once a week or sooner, that is if Im driving daily.

The grinding cant be coming from the muffler or the cat because I just replaced everything on the exhaust from the manifolds back, cat included. Im thinking it is likely the brakes, as it only happens when Im moving and sounds kind of like its coming from rear passenger tire.

As for the idle. I know its not the timing and I know its not a vacuum leak as I went through and replaced all of the lines and the gaskets just to be sure. I also just replaced most of the sensors as I said, including the TPS( I thought it was maybe the o2 sensor but I was wrong).

And ya I know what ya mean about crappy tire, they pissed me off so bad last time I was in there they had to "remove me". HAHAHA

[clariveros]

As for the high idle did you change your fuel filter, and have you tried using that injector cleaner stuff? It is a high idlle but it might be just that something is dirty and the computer is just trying to compensate, good luck

[savage8190]

i just replaced the filter yesterday so well see if that helps when i can start it up again(my instrument cluster is out for repair right now) and ill run some cleaner through

someone told me the coolant loss could be due to a faulty rad cap...any thoughts on that?

[BlazerLT]

Also, clean and reinstall your IAC valve.

[Tstown]

I would bet the leak is the intake manifold.