Okay, I finally have a chance to tackle the minor coolant leak I have, while replacing two more fuel injectors with some I picked up at the junkyard a few days ago. The leak is at the pipe that runs from the front of the intake manifold to the heater core and throttle body. Problem is, I have the 3.1's later version that seems to split in half, with one half screwing into the intake coolant jacket and the other that just clips into it that has the pipes for the TB and heater core. I pulled the two halves apart, since that seems to be where it leaks, and it has two o-rings inside, and a plastic retaining ring. I am not sure if this thing was put together properly in the first place or what (who knows how many times the rings had to be replaced?), but I need a diagram of how this damn thing goes together so I don't screw it up...

:edit: Also, somewhat related (but probably better off in either the Electronics or Cooling forums): Why in the world can't I get the damn cooling fan to turn off? It turns on when the engine starts and off when the engine goes off. The fan switch is NOT grounded (I don't have a switch ) and neither is the connector. If I pull the relay, the fan goes off. If I switch the relay with a known good relay (fuel pump relay since its closest) the fan comes back on. I NEVER start the car with the AC running (I don't have AC anymore, never did work, and I cut off two of the major switch harnesses long after this problem developed), so what else could be the problem? The fan USED to work properly , coming on at around 210 (according to my gauge, which I am pretty sure is off) or so, and going off at whatever temp it went off at, so I'm confuggled...

 

RE: fan always on. On the high pressure A/C line there is a switch. This will turn on the fan once the A/C pressure increases. If the connector is left off of the switch the fan will always run. Or, if the switch is bad the fan will run. To prevent the fan from running need to ground the wire that runs to the ECM.

RBob.

 

Pipe
Head off to the dealer
Buy the parts counter guy a soda
Ask him to pull up the illustrated parts picture of the assembly you question.
The exploded diagram may give ya the clues you seek. Ask the guy for the print out along with pages of the corresponding part numbers, too, to take with you.
IF YOU CAN Buy the coolant hoses from that coolant pipe at same time.
They are dealer items, going outta stock soon.
YET if that hose scoring fails, then find a parts store dealer with GATES or GOODYEAR hoses. Both those suppliers to GM manufacturer. The hoses are preformed hoses. Specific fit, too. Expect $10-$20 per hose. That's how much mine cost me.

 

Coolant pipe has been taken care of.

As for the fan, where is the switch located? I've never had problems with this switch before (A/C never had a charge) and I don't know why it would start all of a sudden like it did...

 

Oh, I wish I could retitle this topic now... Anyways, even with all of the A/C switches disconnected, no wires grounding (double checked) and the wires at the relay fixed, the fan STILL runs all of the time. Is this a fault of the ECM? If it is, I'm hoping that the replacement I am looking at from an 89 will help this...

Or, would putting a fan switch in the radiator help?

 

Yes I did replace my ECM to solve constant fan on condition
Upon opening of ECM I saw a burnt spot on circuit board.
Haven't had the constant fan on problem since that ECM switch.
YET my platform is 1985 & yours is newer so be aware of that one extra detail to your puzzle.

 

Both ECM's appear to do the same thing, and neither one is bad, except for the one I don't use (which has no IAC driver for some reason).

A few years ago, my neigbor bought a '78 Chevy pickup, and he put an electric cooling fan in it. The kit came with the fan, motor, shroud assembly, wiring, and a thermostatic switch that was supposed to be installed by sticking it through the fins of the radiator. I was thinking that since I have to run the fan ground right to the negative terminal of the battery anyways (don't ask why cause I don't know), I could just splice the thermostatic switch in the middle of the ground wire.

 

Well that's what RBob was saying. On the a/c hard line that's bolted to the passenger side main frame rail, there's a small two-wire weatherpack sensor. It's a normally-closed switch, and opens when there's excessive pressure in the a/c hard line.

When you disconnect the connector from that sensor, the fan will run continuosly.

If you've unhooked that small two-wire connector, just stick a paper clip or piece of wire in it so the two wires are jumped together, and the fan should shut off.

It makes for a nice quick way to jump the fan "on" right before you run down the racetrack

 

I had this problem BEFORE I CUT the A/C pressure switch out of the wiring harness. I have some quick splices if need be, but I don't think that's the problem. I'll have to wait for the car to cool down right now before I can take a look at anything.

 

Well if that a/c sensor wire is correctly jumped together, then the normal fan switch is at the back of the passenger side head, with a single green wire going to it.

I'm a little rusty so I don't quite remember the fan diagnostic chart from the GM service manual... if I remember this weekend, I'll try to come on and post it.

 

Forgot to edit my previous post yesterday. I went into the wiring harness, found the two leads that used to have the switch in question on the end, stripped the ends, and soldered them together. Bingo! No more constant fan! Thanks TomP!