I'm at my wits end, I've got a 1986 GL that won't start cold without the assistance of ether, won't idle - seemingly runs fine but it won't hold an idle, it just stalls, and after running the temp soars into the danger zone in short order. I briefly went over the vacuum system, cleaned the egr valve, changed the thermostat and drained and refilled the coolant and the issues persist, just looking for some input from you more experienced subie mechanics before i start blindly throwin money and parts at the damn thing. THANK YOU!

The idle screw could be set for too slow an idle, to begin with. If the timing is off, that could also cause it to idle too slow. Check the timing. The rotor caps also tend to build up a lot of corrosion on the 4 poles inside the cap. The corrosion inhibits the spark. The corrosion can be easily removed with fine sandpaper. The plug wires also corrode inside of the rubber covers at both ends, and should be checked regularly. I have experienced overheating from 3 issues. 1. mouse nest between A/C radiator and main radiator 2. cylinder head crack between the intake and exhaust valves and 3. bad thermostat. Some people also complain of old plugged up radiators.

 

First, check for the old mouse nest. Second, examine the plugs for a build up of tiny white specs from coolant burning with a magnifying glass. Compare all of the plugs so you can figure out which ones are normal and which ones are possibly in a damaged cylinder. Don't lose track of which plug went with which cylinder. If you are losing coolant, then you will also need to be adding coolant to the overflow bottle. If you are not adding coolant then you just dodged a big bullet. If you are, then you are going to have to learn how to change out cylinder heads and get it right the first time. Third, change the thermostat. Fourth, check or change out the radiator for a new one. They are simple to install for anyone and can be bought at many radiator supply stores. Don't buy OEM.

Edited August 22, 201213 yr by scoobiedubie

I did change the thermostat, the cap and plugs are fairly new, as is the radiator; and I am losing coolant unfortunately. I'll check the plugs as you said, because from the sounds of it my cylinder head may be the issue. I could smell coolant when I was driving it but when I parked it and looked around the rad wasn't leaking and it wasn't all that hot.

Sounds like the gaskets are not doing their jobs.. do you hear a bubbling or boiling noise from behind the dash when you start it?

 

And is it SPFI? could be an ECT, but if it's truly overheating and not just lying to you, probably a headgasket...

Before you attempt to change any cylinder head gaskets and then obviously examine the cylinder head for cracks between the valves, spend a couple of hours retightening up the cylinder head bolts. Use a 3/8" x 17mm socket, in order to get into tight places by just removing the cambelt cover. This may solve all of your problems.

Try running without a thermostat. Not really recommended, but it will give you less issues with overheating and will allow you to troubleshoot a little more.

coolant temp sensor if it is not functioning properly it will confuse the ecu makeing it run like that cold and also will make dash gauge malfunction.

I think i tracked down the cooling issue; a heater hose was kinked and leaking fluid down the firewall so i replaced that but I'm still trying to figure out whats causing the idle, or lack thereof... the vacuum lines are a mess so thats what i'll be sorting out today