Help! My 86 Greenwood conv, won't run after heating up!

[johnnyvette86]

Hello All! I am new here! I have an 86 Greenwood convertible with 49,000 miles on it! I am the 2nd owner. I bought the car with a starting problem,all else seemed OK. I had it out cruising and it started to heat up,so I stopped and cooled it down,and found that my electric fan was not working! So.. Replace the fan,and temp sensor,and test ran. Fan motor came on @ 230 ish,and thought all was good. The following day,backed out of my garage and went inside for about 10-15 minutes and came back to a hot,boiling over car,no fan again and really,really HOT! Now, car will start, but won't idle! It has aluminium heads! any Ideas about what I messed up? Any simple tests to start with,or should I just start looking at a new top end? no water in the block,but leaks coolant under where the heater core would be! Any Ideas would be appreciated!!ad

 

[ecss]

Hello All! I am new here! I have an 86 Greenwood convertible with 49,000 miles on it! I am the 2nd owner. I bought the car with a starting problem,all else seemed OK. I had it out cruising and it started to heat up,so I stopped and cooled it down,and found that my electric fan was not working! So.. Replace the fan,and temp sensor,and test ran. Fan motor came on @ 230 ish,and thought all was good. The following day,backed out of my garage and went inside for about 10-15 minutes and came back to a hot,boiling over car,no fan again and really,really HOT! Now, car will start, but won't idle! It has aluminium heads! any Ideas about what I messed up? Any simple tests to start with,or should I just start looking at a new top end? no water in the block,but leaks coolant under where the heater core would be! Any Ideas would be appreciated!!ad

Could be a bad fan relay. No need to run the engine.
Quick check is to Connect pin A to pin B on the diagnostic connector and turn the ignition ON.
Fan should run. If it doesn't verify at the fan relay the Dark Green/White wire is being grounded by the ECM.
If it is, the relay should energize and pass 12 volts to the fan motor on the Black/Red wire.

As for verifying if any damage was done from over heating.

First do a coolant pressure test.

Rent the kit from Advance Auto or Autozone.
You manually pump up coolant pressure to around 16 psi and see it it holds. If it leaks down that's bad news and you need to locate the leak. In your case you said you have a leak in the heater core area?

If the water was clear are you certain it wasn't condensation from the AC evaporator?

If there is white smoke from the exhaust it usually indicates one of the cylinders is burning coolant.
Pull the plugs and look for one that appears as if it was steam cleaned.

Do a compression test and compare the compression numbers to the other cylinders which could point you to which cylinder has a problem.

Any reputable machine shop can pressure test the heads, check for cracks, mill the head and perform a valve job.

 

[johnnyvette86]

All Great places to start! thnks for the direction! Ill keep you posted!

 

[Hib Halverson]

Welcome to the CAC "johnnyvette".

After you troubleshoot the fan system and get that squared away then you need to replace the heater core.

Refill the system with coolant making sure you eliminate as much air bubbles as you can then start the engine and run it until the thermostat opens then shut it off. After it cools, remove the cap, fill the system to the appropriate level then run a pressure test and look for leaks.

If there are no obvious leaks but the system will not hold pressure, assume a cracked head or a failed head gasket.