The big 2.3E coolant temperature mystery

[newsh]

I may have a new radiator that will fit. I bought it for a car which caught fire before I could fit it! I'll get the part number.

[Robertbozic]

You need a new radiator, the thermal image shows that.

Given you can't get a radiator with an integral oil cooler for the automatic I'd get a new radiator without the cooler which you can get. Delete the auxiliary radiator and use the space to mount an oil cooler radiator for the automatic transmission. https://sharpedgeshop.com/collection...-knives/nakiri

Once you leave an engine stationary for a long time at idle the kitsune miniatures temperature it reaches is only controlled by the temperature the electric fans kick in so will be higher than normal.

Looks like it's time for a new radiator. You can go for one without an integral oil cooler and install a separate oil cooler radiator for the automatic transmission in the auxiliary radiator space. Idle time can make engine temps rise due to fan control.

[K Simmonds]

I seem to recall I removed the starter motor to improve access, then use a long extension on prefferably a 1/2" drive socket, though 3/8"'s will do the job.

[Luuk813]

So I made my start on removing the head yesterday. So far I removed the injection system, airbox, most vacuum lines & the upper intake manifold. I might remove more then absolutely necessary, but I see this as a perfect moment to check & thoroughly clean the components.

I however for the life of me can't figure out how you're supposed to remove the bolts holding in the exhaust downpipe to the exhaust headers. They have to come loose to get the head off, but there doesn't seem to be enough clearance to get tools in there. I can also image that you would need a lot of force to get them off, once you get to them, since they've been heatcycling since 1993. Anyone got experience in removing these bolts to get the head off? If so, what's the method you used?

[K Simmonds]

2000 Thousand Euro's to replace an NG head gasket is a total rip off, I'd find another garage or do it yourself!

It's a days work to the job plus a hold up to skim the head which will of or least should cost about 50-70 Euros, including changing the timing belt.

A gasket set for an NG engine shouldn't be anymore than 100 Euros and timing belt kit the same, I can get the pair about £100 in this country. Unless your cambelt is new then I would renew whilst it's all apart, it's a very easy job on these engines. The only hard bit is dealing with the insanly tight crank bolt you need 3/4" drive breaker bar and an impact 27mm socket to undo it, and retorque it up.

The part that takes the most time is removing the front end of the car to get decent access.

I've never heard of an NG engine cracking the block or head, unlike the turbocharge 20V the heads don't get anything like as hot even if your car has been overheating a little.

Use a Vikor Reniz headgasket set and bolts and Gate's cambelt kit. Find a good local machine shop to skim and clean the head and set about it yourself.

I charged the customer £50 for the last cambelt I did on a 7A engine which is much the same job, granted was mates rates but it would of cost £100 if I'd charged full price. I'd probably charge around £200 + parts and a skim to do a headgasket on an NG motor.

[Tractor Dave]

Well done for establishing the issue.
Doing the head gasket isn't too difficult. I would do the water pump, thermostat, timing belt, valve stem seals all at the same time. Also replace the short coolant hose on the left of block. The Haynes manual for Audi 80 covers almost everything.
A good machine shop will pressure test your head for you.
I would still get a new radiator though.

[Luuk813]

Well, I just got around to doing option 2 today, checking for exhaust gasses in the coolant. It looks like Tractor Dave was right on this one

After driving for about 20 minutes at 60km/h the temperature got up to 105, but didn't exceed it. Nevertheless the tester the garage used clearly showed that there where indeed exhaust gasses mixed into the coolant/water. The garage wanted around 2000 euro's in mostly labor to replace the headgasket, but they told me there is also a possibility that it's not the gasket, but a crack in the block or head itself.

For that amount of money I'll give replacing the headgasket myself a try, since the garage understandably couldn't give me a guarantee on if those 2000 euro's would actually fix the problem. I have already removed the upper intake manifold & the valve cover on this engine before, so It should be doable to remove the head if I take my time. The only thing I'm slightly worried about is having to mess around with the timing belt, but I'll cross that bridge once I get to it.

[johne]

You need a new radiator, the thermal image shows that.

Given you can't get a radiator with an integral oil cooler for the automatic I'd get a new radiator without the cooler which you can get. Delete the auxiliary radiator and use the space to mount an oil cooler radiator for the automatic transmission.

Once you leave an engine stationary for a long time at idle the temperature it reaches is only controlled by the temperature the electric fans kick in so will be higher than normal.

[Luuk813]

Your comment above would suggest the 'stat is open if the fan is about to kick in. In that case I'd get a new radiator.
Regarding air locks, if you can do your best to fill the system with the tank held high and coolant is at the bleed points.......then run the engine with the cap OFF until the 'stat opens should purge any air from the system.

Thank you for your advise. I'm set out on following these steps starting next week:

1. Once more try to bleed out any air on the way you suggested.
2. Do a coolant exhaust gasses test to make sure that my head gasket is not blown.
3. Assuming that it's all good, try to source a fitting radiator (with transmission cooler) somehow or contact some shops to try to refurbish my current one. The auxiliary one is still available brand new from Audi Tradition luckily, so I'll probably switch that one out too to get rid of the corrosion.
4. If by now the problem still persists, it must be the coolant pump, so I'll contact a garage to get the timing belt & coolant pump done.

I'll update this posts with my findings . One thing just to be sure: I'm having some local people telling me that it's OK and even expected for it to reach those temperatures after idling for some time. Anyone let theirs run to idle for an extended amount of time, that checked the temperature gauge? I can't imagine that this is expected behavior, but I just want to ask your guys experiences to be absolutely sure of it.

[John.]

The picture above shows up how the radiator heats up, just before the fan kicks in.

Your comment above would suggest the 'stat is open if the fan is about to kick in. In that case I'd get a new radiator.
Regarding air locks, if you can do your best to fill the system with the tank held high and coolant is at the bleed points.......then run the engine with the cap OFF until the 'stat opens should purge any air from the system.

[K Simmonds]

You either have a duff thermostat, an airlock (very likely with NG's engines) or the gauge is simply wrong due to a dodgy sender though I think you've ruled that out.

[VW-1964]

I will try to look for it. Can't see on the thermal picture if the coolant hose coming from the thermostat is warm. I raised the reservoir as well, but ended backfilling the system through the bleeding screw on top of the radiator with a small funnel. An armature solution, but solved my issue :-)

Looking at the amount of gunk at the thermostat housing, it could indicate that you are not getting much flow through the thermostat. If you have an air pocket, you can feel the temperature difference on the hose when the system is warming up.

[Luuk813]

Have you checked that you don't have an air pocket on the top-side of the thermostat. I also have an NG engine in my 1991 Coupe, and getting the system properly bleed is key. Before finding the write-up somewhere here on the forum, I was having an air pocket causing the thermostat not to open, resulting in the temperature raising. Getting it bleed correctly solved my problems.

Peter

Hi Peter, do you perhaps remember witch exact write-up / procedure you followed? There are a lot of slightly different advices, but having something that should work for sure for the NG would be nice. I use the method of raising the coolant reservoir after shutting the car down, and it will burp out air everytime I try to bleed it, no matter how often I try.

[VW-1964]

Have you checked that you don't have an air pocket on the top-side of the thermostat. I also have an NG engine in my 1991 Coupe, and getting the system properly bleed is key. Before finding the write-up somewhere here on the forum, I was having an air pocket causing the thermostat not to open, resulting in the temperature raising. Getting it bleed correctly solved my problems.

Peter

[Luuk813]

I just used my works old school FLIR camera, and might have found something interesting. First off, the temperature gauge is 100% accurate with the temperature of the water that flows by the MFTS, so it's good to know that I can trust that reading. The fan thermo switch in the radiator is also working correctly; the fans turn on at speed one once the water reaches around 95c there, just like the manual says it should.

What is interesting to me however is that the radiator is not heating up evenly. There is a big difference in the temperature on the right hand side, where the dent is. I saw differences of 100c on the right, versus only 55c (!) on the rest of the radiator:

PXL_20230817_160626231.MP.jpg

The picture above shows up how the radiator heats up, just before the fan kicks in. The reservoir on top heats up evenly, but the radiator fins accumulate heat mostly at the right side. Please ignore the hot tube coolant tube on the left, and the cold power steering line on the right (marked with white arrows). I couldn't get them out of the shot. Once I found a CompactFlash reader I'll upload the pictures I made so that you can get a better understanding of what I mean.

Am I correct in thinking that this is at least A problem, even though it might not be the only problem?