Heater core is leaking and now it won't start!

[RoyalViking]

Oh boy,

The front and rear intake manifold seals had swelled (silicone) and the engine was leaking quite a bit of oil. I had planned to pull the car into the garage to put the new intake gaskets on. However, I was suspicious of a coolant leak. The previous owner had used stop leak at some point in time. I pressure tested the system at less than 20 lbs psi and noticed the pressure dropped quickly. I left the pressure tester on and started the engine to see if it was a head gasket. I discovered the leak as the engine warmed up. I had steam coming out of the heater/def vents. The car stalled and would not start for a while.

After I removed the pressure tester I tried to start the car and it would not run. I got it to run for a minute and then fire once more while trying to start it.

My guess is the leaking heater core has gotten the ecu damp. I left it sit thinking it might start the next day. I noticed the check engine light does not light up when I put the ignition to the on position (prior to trying to start). I removed the trim panel under the heater core and it had antifreeze all over it.

How difficult is it to remove the heater core?

Is my ecu toast?

Roy
1989 C4

 

[JonM]

Well Roy...the consensus is that the heater core is part number 000001 and the rest of the car is built around it...Go to SEARCH>>ADVANCE SEARCH>>TYPE IN "HEATER CORE" >> SEARCH IN C-4 TECH >>>SEARCH...you will see others who have done it lately and written about it...I think 69MYWAY did it recently

 

[JonM]

Another note...The ecm is tucked up behind the breadbox and the core is enclosed...I don't think it should have gotten wet. How hot did the car get before you shut it down?

 

[RoyalViking]

Another note...The ecm is tucked up behind the breadbox and the core is enclosed...I don't think it should have gotten wet. How hot did the car get before you shut it down?

After it got to normal operating temp. I thought the coolant would have drained out of the heater box. After seing it on the lower dash panel I am not sure what to think. The drain may be clogged?

I live in New England and the weather had not gotten to where I can work outside for very long. I'll take a look at the heater core replacement thread.

 

[JonM]

Good luck...I am on the southern end of I-91

 

[RoyalViking]

I replaced the heater core (finally). I have to admit this job was tough. Not complex, but difficult to get my hands in the confinement of the dash area. I've taken plenty of pics and plan to post them some time if anyone else has to do this.

I understand now why the electronics were saturated. The ECU is mounted next to the heater box. When the heater core went the interior was full of steam. From the looks of it the core was leaking for some time and the previous owner used some kind of lock stop to plug it. Oh, well so much for that.

The foam that seals the heater housing openings was not useable and is discontinued. I made a hot wire foam cutter and made a new one. It's pretty close to original. I have the heater core in place and bypassed it till I can flush the system.

Yesterday I tried to start it. I've had to recharge the battery (it's not taking a full charge). The engine didn't start first try but did on the second. Rather sluggish at first. It didn't want to rev much higher than idle. I got out and moved the throttle plate by hand and it would not respond. It backfired through the intake. When I gave it full throttle it rev'd without a back fire and sounded strong as ever. I took a look at the voltage, it was at 10 volts when I first looked. I then checked the dash and noticed the check engine light was on. The voltage dropped to 9 volts and then the engine died. I hooked up a XP240 diagnostic tester and found no codes (did show engine data). I used the jumper between A and B terminals and found code 44 (lean on left side). I had already replaced the fuel pump relay (intermittent fuel pressure drop, after removing relay found it rattled). I checked the TS and there are no breaks in the resistor, the resistance changes gradually without blank spots as I open and close the throttle plate.

I know I need a battery and hopefully not an alternator. What else could this be? :confused

 

[gearshift]

Replacing Heater Core

I am having difficulty getting the heatbox out to get to the core. Removed dashboard, passenger side dash, etc. It is hanging, but there must be a bolt or two hiding.

Any advise?

 

[RoyalViking]

I am having difficulty getting the heatbox out to get to the core. Removed dashboard, passenger side dash, etc. It is hanging, but there must be a bolt or two hiding.

Any advise?

There are two screws at the top of the box that you may not be able to see. Check if you have not removed enough stuff (ECU, etc.) to get to them. There are three across the bottom as well. The screws can be removed with a 1/4" drive. Did you removed the air damper motor? Let me know if this helps.

Now if someone could offer help with my off idle problem I'd be all set.

 

[fast.asleep]

I replaced the heater core once. When I was done I said "Never Again!"

If you only drive the vette in the summer bypass the heater core. It's a lot less work and a lot less $$

(I know it's a little late now but keep it in mind for next time. -It's what I'm going to do)

 

[RoyalViking]

Off idle performance problem solved!

I finally found the solution to my problem with the off idle backfire!

The car has sat since 2002 and I had charged the battery every so often. The battery had taken quite a while to charge as time went on. I tried starting the car with a different battery and it runs fine!

If I had driven it daily the problem would have been an easy solve. If you have had to recharge the battery after it has sat and the car won't run, try the battery. What a relief!