gordyboy

I've read through numerous threads I found on the forum concerning overheating and picked up some good tips, but none of the scenarios seem to be the same as mine.

88 na has always seemed to run a bit warm, but being in the Pacific Northwest it wasn't a problem. Now that we've moved to Nevada it is. It's cooled off a bit now but the car still overheats when the air conditioner is turned on. If I don't run the air conditioner it's fine and the air conditioner seems to work well.

When it was really hot a few weeks ago (110 - 120 degrees) it would come close to overheating even without the air conditioner running. It also seems worse if I go faster, if I slow down it cools off. When I shut the engine off at least one of the fans continues to run, and when it's running I've seen both fans going so I don't think it's the fans.

I had the cooling system flushed a couple of months ago and last week I tried bleeding it to make sure there was no air but none came out, just a steady stream of coolant.

Any ideas why it would run so hot, particularly when the air conditioner is turned on? How about the fact it's worse if I go faster, could the belt be slipping on the water pump?

Peckster

A new rad fixed similar that problem in mine. Flushing usually won't fix a rad that's plugged up if that's your problem.

adrial

Have you verified that the fans are coming on?

ERAU-944

the thermostat may be stuck closed or partially open (read: VERY partially). does it take a long time for your car to warm up? or does it warm up pretty normally (within a few minutes). you should be able to drain the coolant, put a hose in the top left, and blow coolant/water out the bottom right with hose pressure. if it doesnt then its plugged up. i'd test before replacing. i pity you if it turns out to be the thermostat, they are NO FUN to change at all esp. in HIGH heat situations.

good luck,
-Michael-

MM951

Michael, I have a 280zx and it overheated very quickly, so I just pulled out the thermostat for now and it doenst overheat....will that solve his problem? Turns out my stat was broken, gotta order it...so the Z is off the road too...

gordyboy

I guess that would narrow down the problem. If I pull the tstat and it doesn't overheat it's kind of the smoking gun isn't it? I it still overheats then it's something else. I was thinking that maybe the belt was slipping on the waterpump and that it would be worse at high speeds (?).

ERAU-944

if his stat is broken it will partially solve his problem, but it will take forever to warm up and the car may never get to full operating temp and cause poor gas mileage. my dads trucks thermostat is stuck open, and it never gets to operating temp, KILLS his gas mileage, the truck runs in perpetual warm-up mode (lets it rev higher before shifting (not a problem for me since its turbo diesel )). so in short, it'll fix it, but if i'm in there with the torture of removing it you'd better beleive i'm not gonna put off the torture of putting one back in at the same time, and bleeding coolant everywhere. they aren't that expensive either.

-Michael-

ahofam123

I'm thinking radiator. Before spending $200 on a new radiator though, I would borrow an infrared thermometer from a mechanic or someone and verify that it is overheating and that it isn't a mis-calibrated guage.

88_944

I agree, try replacing the thermostat, but it could be the Gage that is actually causing a problem. Try replacing BOTH water temp. sensor AND fuel injector temp. sensor ( the water temp. sensor sends info to your Gage while the fuel injector sensor send the information to the DME or ECU unit). Both sensors are relatively cheap and can be replaced with in about 10-20 minutes. The intake boot has to be removed to replace both sensor's and place a new wire for the water temp. sensor. If then all fails, try replacing your t-stat......... hope this works

ERAU-944

if the thermostat is stuck closed, get the car warm while driving, then stop, and touch the bottom of the hose on the passenger side on the bottom of the radiator. if the car is warm, and the tstat has opened, it should be hot down there. if its not hot, the tstat was stuck closed. thats how i told the tstat was bad on the parts car.

-Michael-

gordyboy

A couple of points...

The engine gets HOT, I mean when I pop the hood I just about have to be wearing asbestos gloves because even the hood latch is hot. The upper and lower rad hoses feel HOT.

If the tstat was stuck closed, would the dash guage climb? Also, the heater blows hot so it seems that hot water is circulating through the heater core (?). Through all last winter it warmed up quickly and blew heat quickly. I'm not sure how often I'll use the heater in our new home ;-)

Ski

1. Bad thermostat. - if you pull and not replace the 944 thermostat, you will circulate water in the water pump. When the thermostat opens it seals off a bypass port for force water through engine and radiator.
2. Bad seal on inside of water pump. see "circ" above
3. Fans are shot or thermal switch
4. Radiator is getting plugged,
5. Timing belt is loose.
6. Bad sender and/or gauge.

ERAU-944

yup, the temp sensor is in the engine. the parts car had same symptoms. HOT hood latch.

good news - t-stat is cheap fix

bad news - its a PITFA to get in/out

-Michael-

Charlotte944

BTDT with my '87.

I bought it last December, but didn't put very many miles on it until recently.

With the warmer weather I noticed the temp gage was always between the marks, and would climb to the upper mark and stay there if the A/C was on, or if I pushed the car a little.

I replaced the head gasket, water pump, thermostat, coolant hoses, radiator cap, belts, and flushed the system, all with no success.

Just this past weekend I borrowed a radiator, and the change was dramatic. On a 90 degree day (today) with the A/C running the temp needle hung just above the first mark, right where it should be.

Here is an easy test:

Start the engine and let it idle. Listen for the fans to come on and make a note of where the temp needle is. If the temperature does not drop enough for the fans to cycle on and off, the radiator is clogged. With my '87, the temp needle would go the the upper mark, the fans would come on, the needle would drop not quite half way, and the fans ran continuously.

Paul C 944

It sounds like a radiator is the main culprit. Dont rule out ground issues,they can give misleading temps on the gage.