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Discussion Starter #1
I have bought a replica car with a N* motor. The motor is located in the rear of the car, and the coolent runs through through long tubes to rad, located in the front end. Not sure what year the motor is, or the milage. Car has a digital dash, the water temp runs up to 255, and the limp home mode kicks in. I'm running a 180 thermostat. Would the distance the water now runs, cause the car to oerheat? Would a lower thermostat help to keep the car cooler? The builder put in a custom built brass RAd, with one cooling fan that runs all the time, I just installed a second one, but no change. Any ideas?
 

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2010 DTS
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Check the purge line for flow. Check the surge tank cap to be sure it is holding pressure. Check the water pump belt tensioner. If all are OK, then get a block test kit from Napa and test the coolant for exhaust gases. When you figure it out and get it running right, put the correct thermostat in it.
 

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Discussion Starter #5
Ranger,

Before I took the car into paint, and it was overheating, I lost most of the coolant, I have not yet replaced it, so I'm running mostly water in the system. Will coolant help to bring the temp down? Also prior to paint, the car would boil over at 245, not it does not. It gets hot but, no boil over at 255. What is the correct Tstat for the car? I have read posts here that say 180 is correct?
 

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I think the OEM stat is 210. Maybe 200. Coolant won't bring the temps down. Actually water is a better coolant. The only reason for "coolant" is freeze and corrosion protection.
 

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Discussion Starter #7
Thnaks for the good info Ranger, I will check out all your suggestions today, hope it's one of the simple issues, not the head bolts.
 

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'99 SLS, '05 Deville, '87 Porsche 944
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You need to check and make sure you are getting coolant flow to the radiator and that the radiator fan is running correctly. Have you reached under the car to make sure that the coolant pipes on both side of the car are heating up? If they are not you may have a blocked radiator or an air-lock situation. Look under the car and make sure that the coolant pipes haven't been crushed by some half-wit at a garage (very common problem with Fiero's). After it overheated and boiled over the first time did you just add water without doing anything else? Typically these are very difficult cars to fill the coolant system and get all the air bubbles out, try backing it onto a set of ramps to get the rear in the air then take your time and add the coolant. If the fan is not coming on there may be an issue with wiring or a bad relay. Because your car is fiero based you may want to go over to Pennock's Fiero Forum and check out the technical section.

Good luck.
 

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Discussion Starter #9
Getting movement, both pipes are hot, tried all the burping tech stuff out there, I think that maybe the digital gauge may be the problem, is the sending unit near the intake manifold back near the T-stat? I might try a manual temp gauge and see what I get.
 

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Discussion Starter #12
Thats pretty sweet. Bet it flys with a N*. Fiero based?
Thanks, It's still a work in progress,I just put in 1.5 inch lowering springs in the front to drop the front end, need to get a full alignment, and put it on the highway. It's got the full Z06 braking system. Once I get the oerheating problem taken care of, it's going on ebay.
 

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Discussion Starter #13
Ran the car today and still overheats. At 255 water was comming out of the overflow tank, but it was not hot, it was cool. I opened the pressure valve on the front rad cap, and air came out, then more water from the overflow tank untill i closed the cap valve. The rad on the pass side is cool, a little warmer on the drivers side, but not real hot. When it cooled down, I opened the rear cap, and I had lost a lot of water. I filled from the rear and could hear a gurgel sound comming from the block as it filled. I started the motor with the rear cap off, at 160 hot water and air started comming out. I shut it down, added more water, capped it, and started it again. This time the temp ran to 195 and stoped there. After about 2 minutes I shut it down. I will rty a road test in the morning and see what happens. I have 2 fans mounted, 1 in front of the rad pushing, 1 in the rear pulling. Fans are hot wired to on when the key in turned, is this push pull helping or hirting air flow?
 

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Ran the car today and still overheats. At 255 water was comming out of the overflow tank, but it was not hot, it was cool.
Huh? 255 IS HOT!
I opened the pressure valve on the front rad cap, and air came out
I'd get a block test kit and test for exhaust gases in the coolant. Kind of sounds like you are pressurizing the cooling system with exhaust gases from a leaky head gasket.
 

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Discussion Starter #15
Ranger,

If this problem is so large, why has there not been a class action suit against GM to repair the motors?
 

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I don't think it is THAT large. Larger than it should be, but not THAT large. Other than that, I don't know.
 

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Discussion Starter #17
Huh? 255 IS HOT!

I'd get a block test kit and test for exhaust gases in the coolant. Kind of sounds like you are pressurizing the cooling system with exhaust gases from a leaky head gasket.

Ranger, is it possible that the builder crossed the hoses, with the car running I pulled the rad hose on the drivers side, no water comming through. The motor was reversed in my car, the fan belt is on the pass side, the thermostat on the drivers. Also under the throtle body there are 2 hose outlets, one has a hose hooked up, the other does not. Could
this be part of the problem?
 

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Serpentine belt on a N* is always on the passenger side, water pump is always on the drivers side near the transmission. The two small hose outlets under the throttle body are part of the purge line plumbing on N stars and its used to warm the throttle body. One line connects between the throttle body and a hose barb on the water pump housing, the other line goes to the top of the surge tank. this is how any air bubbles in the coolant get purged out of the system. If you don't have a purge line hooked up (doensn't really have to go thru the throttle body) the system will get air bound and not circulate any coolant in the system.

The hose connected to the water pump cover where the thermostat is located is the hot water out of the engine hose, the cool water return from the radiator connection is below that one.
 

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Discussion Starter #19
Serpentine belt on a N* is always on the passenger side, water pump is always on the drivers side near the transmission. The two small hose outlets under the throttle body are part of the purge line plumbing on N stars and its used to warm the throttle body. One line connects between the throttle body and a hose barb on the water pump housing, the other line goes to the top of the surge tank. this is how any air bubbles in the coolant get purged out of the system. If you don't have a purge line hooked up (doensn't really have to go thru the throttle body) the system will get air bound and not circulate any coolant in the system.

The hose connected to the water pump cover where the thermostat is located is the hot water out of the engine hose, the cool water return from the radiator connection is below that one.


The only hose going to the surge tank is from the rad overflow outlet just below the rad cap in the front of the car, which is where the surge tank is.

Where would the purge line oringinate from?
 

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There is a pipe nipple on the crossover manifold, just behind the water pump cover (if you were looking straight at the water pump from the dirvers side fender it would be at about the 4 oclock position). On an STS its actually holding the lower corner of the accelerator bracket onto the crossover manifold. The nipple is connected to a 3/8" tube that runs to the top of a stock cadillac surge tank. The nipple is how any air that gets to the water pump is vented off, without it the water pump will become air bound and not pump anything. Do a search on purge line, you will find all you ever wanted to know about it.
 
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