I have an 88 NA that I just got back from the shop for an electrical problem and now the car is running very hot. On the temp gage is right at the edge of the safe zone. Today I replaced the thermostat and that did nothing for the problem. When I got home today the coolant was being forced into the overflow bottle and draining out the hose there.
The motor is stock, except for k&n cone filter and 5th and 6th ports are wired and I've removed the a/c stuff and the air pump.

What gives? I'm kinda thinking cavitation? I can keep it cool by keeping the revs down below 3000.

Thanks for any help.

 

It sounds like your radiator might have seen the end of its days, how many miles does it have? What was the electrical problem that they fixed?

-Kris-

 

165045 Miles

Had a short in the wiring harness and burned out 2 relays.

The system still has plenty of pressure.

 

One of 213 things it could be is a simple radiator cap failure letting the water go into the overflow. Have to admit my first thought is bad seals but recently I had a bum f--- radiator cap doing just what yours is doing. Also if its happening just at idle it could be the fan clutch. Not the fan clutch if it overheats at hwy speed. Could just chunk the thermo out altogether and see what happens. Does not cost a cent to do that. My 86 and 87's all run below the bottom 1/4 during summer in Texas . I understand the newer models read different on the gauge. Yeah! Radiator cap. Cheap fix. Don't wanna rebuild, just yet.

 

I have an 88 N/A and i have that same sort of problem. changed the thermostate, nothing. drained the fluid, nothing. it just runs like that. i get real nervous but she just runs that way. HKS intake R/B header presilencer. sometimes i get frustrated when shes hot and rev the hell out of her and the temp goes to normal. i now call her CHRISTINE.

 

Mine kind of did the same thing, only mine smoked badly(VERY BADLY)...I later found that I actually blew the corner seals(coolant seal) and thus my GTR transplant
If your car is smoking under 3K RPMs, you may have the same thing...when the seal blows, your car will run, it just lets coolant slip through and it gets burnt out w/ the rest of the air/fuel mixture...thus the smoke......

 

Time for a new radiator. 160K is a lot of miles. You can mess with radiator caps and thermostats, but at this point, IMHO, the problem is one of three things: Waterpump, Radiator, engine seals. If the waterpump isn't weeping, I'd go with the radiator.

PaulC

 

Anybody have any experience with waterpump cavitation?

I am almost sure this is where the problem lies. It only gets hot at highway speeds. It will stay cool idling all day.

Just wondering hot does a radiator wear out?

Or does it just get plugged with crud?

Thanks for the help guys.

 

I chased overtemp problems on my 87 for weeks. Here is the short version.
The water pump housing (the casting behind the pump) erodes at high revs. I found the bypass valve seat under the thermostat eroded. The wall between the inlet & outlet sides had a 6mm hole. All this bypassing gives symptoms like a partially blocked radiator. I molded repairs with Bondo Marine Epoxy Putty Stick. The new owner says it is still holding. The other thing that sneaks up on you is the fan clutch. On the series 4 version the fan pulls hard up to about 3500, and then maintains ~3500 as the engine revs higher. Mine was slipping at 2500. You can get the fan clutch to bite better by bending the bimetal strip outward. I ended up buying a new fan clutch.

 

Jeff88...plugged with crud. Radiator shops *rod* the radiator out, as in take the ends off and shove a rod thru to clear the passages and then put it back together. At least they used to do that.

 

Can't you take the radiator off and clean it yourself? What would you use? Like that stuff that cleans rust and used to clean your shower? Think that would work? Thanks.

 

Message to jeff88:do you have all the plastic pieces in place?the undertray,the 2 pieces in front of the rad.If not replace them because car will run hot without them.

 

Hmmm...are you talking about the bottom panel you have to take off to get to the bolts to take the fan shrow off? Because my car is running hot & I haven't put that back on yet. Hmmm...could that really make my car run a little hot? Thanks.

 

^^

 

If ANY of the plastic panels in front of or below the radiator are missing the car will run hotter than if they are in place.Also if you have any debris,leaves,dust oil/dust or crap in general on the outside of your radiator the car will run hotter.
The idea is to maximise air flow through the fins of the radiator and thus carry the heat away.(Heat Transfer 101)

 

Hmm...as soon as I get home that piece is going back on. Hope it helps alot. Thanks.