EA82T new problems after unrelated repair

[SiriusBlack]

Hey everyone, I've got some new problems with my 87 GL10 Turbo XT. I'm hoping you all can help me out again. I pulled the coolant passage off the back of the intake manifold to replace the gaskets and the thermo vacuum valve as they were leaking coolant. To get it out without pulling the entire manifold I had to remove the turbocharger, distributor, knock sensor, and the throttle cable bracket on the bell housing. I just recently got it all back together and after some issues timing it (since I removed the disty) we finally got it to time at 25 degrees BTDC. Now however it tries to idle at 3000 rpm and heats up really fast and overheats despite my upgraded dual core cooling system. We haven't done tons of troubleshooting yet, just looking for things to try while I do so. It ran like a dream before I took it apart for the leak. Any suggestions? Thanks in advance.

[6 Star]

Throttle cable out of adjustment?

Or a leak coming from the mating surfaces of one of the components you removed?

I'm not as familiar with the XT or the Turbos, so hopefully someone else also chimes in

[el_freddo]

You could have a number of issues. Before GD says it, burn it and get something old school GM  

Serious now... you could have an issue with your HGs depending on when they were done last; there could be an air leak in the system or a stuck thermostat - or both!

25 deg BTDC is a bit much isn’t it? The MPFIs over here were all set at 20deg with some plugs connected under the dash while adjusting so the computer didn’t mess with the timing while you were adjusting it.

Other things to look at, what’s the condition of your water pump?

It could be worth getting the nose as high in the air as safely as you can, run for a minute then let it cool down. Check the coolant level. If it’s down it could be worth pulling the thermostat housing to see what that’s doing. Test it in some water (hanging from wire in the water, not sitting on the bottom of the pot while it’s being heated). Replace if dodgy.

While that is out full the engine with coolant through the thermostat hole if coolant is needed. Squeeze the heater hoses to try and displace any air in there and top up as needed again.

Refit thermostat and rad hose, back fill rad hose and connect to radiator. Turn engine on and slowly/steadily fill the radiator with coolant. Monitor temp etc and continue filling with coolant in small amounts when it lets you. Throw rad cap on, hold some revs for 10-20 seconds, let idle then shutdown. Let it cool. Check coolant level and top up as needed.

The other thing to look at is your coolant temp sensor and TPS - make sure they’re working within spec and that the throttle cable isn’t holding the throttle open a little. If it is back this off and see if idle changes.

Let us know how you go.

Cheers 

Bennie

Edited July 27, 2021 by el_freddo

[SiriusBlack]

25° is what the turbo model calls for, says so on the under hood sticker. The water pump is brand new, head gaskets are 17 years old but have almost no miles on them, the car ended up sitting after the gaskets were replaced. However, as I said it ran like a dream before I took it apart for the coolant leak. Thermostat and coolant temp sensor plug are both brand new. I had learned from an ancient post I dug up a couple years ago that the ECU has to be put in test mode for the timing to be set, just connect the green jumper wire.

Edited July 27, 2021 by SiriusBlack

[DaveT]

+1 regarding the green connector and test mode.

[GeneralDisorder]

To run at 3k RPM with the throttle closed it's getting air from somewhere - you need air for the engine to run at that RPM so it's getting it somewhere. If the throttle is closed you have a leak. And that means unmetered air which means it's going to be running lean and that will drive up the temp and run the fuel trims positive if it's even attempting closed loop operation. 

Fix the vacuum leak first. 

Or swap in an EJ22 and get more power without the messy unreliable turbo EA garbage. 

Or.... yeah..... burn it and get a V8. Although I would sell it to some other sucker and forgo the weenie roast. 

GD

Edited July 27, 2021 by GeneralDisorder

[Step-a-toe]

High time for me to reset my password in order to get back in here after device change .

87 is flat manifold ? How is the (hard as ) rubber air transfer hose from above the thermostat housing to inlet manifold? If you have one

The 25 DBTDC is interesting, as all our Oz turbo EA82 are 20 according to bonnet sticker and manuals.

I say easier to resolve this than EJ it

Did you check the coolant transfer casting internals when you had it off, and replace the tiny welsh/freeze plugs you see when it removed? Those little bastards rot after 20 years

[SiriusBlack]

@Step-a-toeI did replace the freeze plugs, knew they were a worry spot as well. I'll have to triple check the timing, but I could've sworn the bonnet sticker said 25°. I'm going to reset the ECU and double check the timing, I'll also go over the hoses with a fine tooth comb. Sounds like odds are one got screwed up and I have an air leak.

[subaru1988]

On 7/27/2021 at 6:39 AM, SiriusBlack said:

25° is what the turbo model calls for, says so on the under hood sticker. The water pump is brand new, head gaskets are 17 years old but have almost no miles on them, the car ended up sitting after the gaskets were replaced. However, as I said it ran like a dream before I took it apart for the coolant leak. Thermostat and coolant temp sensor plug are both brand new. I had learned from an ancient post I dug up a couple years ago that the ECU has to be put in test mode for the timing to be set, just connect the green jumper wire.

The FSM for an '89 says 20 BTDC @ 800 RPM for all models SPFI and MPFI with Turbocharger. I know you have an '87, but it can't be all that different. I'd make 100% sure the rotor points directly- as in dead nuts on- at the #1 post on the distributor before checking the timing again if you removed the distributor.

FWIW, my car was timed 5 or 10 degrees off (too far advanced) before and after my timing belt job, and I'll tell you what. It runs so much better with those extra 5 degrees out of it. I'm not sure why, because you usually see a small seat of the pants improvement with advanced timing.

Edited July 28, 2021 by subaru1988

[ferp420]

the dizzy could be off and its firering on a exhaust stroke  

[SiriusBlack]

I fixed the primary running issue, throttle cable did end up out of adjustment and was keeping throttle open. Still have an issue though. Despite the dual core radiator it tries to overheat if you sit still for more than 5 seconds. It's like 100 degrees outside here now, but it should handle that. It did fine staying cool before the repair, just leaked which is why I took it apart.

Edited July 29, 2021 by SiriusBlack

[ferp420]

from the original post it seems the only thing done to the car that would cause it to over heat is the wrong timming the crank and the cam and the dizzy have to be timed together if its off it wont run right and will over heat right away if the cam and the crank are off you can still time the cam to the dizzy and it will run but vary hot just like if your a tooth off on the timing belt  its eazy to get wrong cause the dizzy moves as its installed so when you set it you have to account for that movement if not your a tooth out 

[SiriusBlack]

Alright everyone, I've got it running like a dream again, burped a ton of air out of the cooling system. That took care of the overheating. Thanks for the suggestions.

Stay tuned to the boards, I'm hoping to try an experimental fix for factory XT air struts that I thought up. It should at least help till my dad and I finish figuring out how to modify modern universal struts.

Edited July 30, 2021 by SiriusBlack

[6 Star]

Sometimes its just the darn simple things, finding them can be the tricky part.
Amen it was just the throttle cable and air in the coolant system.
Sidebar: Escape from Azkaban lately?