Carrera 3.2 no flow to front cooler

[rbarton]

Hi all, hoping for some help with my '86 Carrera. I recently got the car running again after a (pro) top end rebuild and various 'while the engine's out' projects. It runs great, but the temperature gauge is going high. It reached the 10 o'clock mark the last time I had it out, which I believe is around 248 F. Way too hot.

Immediately after that drive, I felt the front oil cooler lines inside the front wheel well and found that they were at ambient temp - no flow through the external thermostat. I ordered a new external thermostat insert from Pelican and installed it. Note that both inserts slid easily in and out of the housing.

Running the car again, the gauge went to 9 o'clock before I shut it down. Again, there was no heat in the front cooler lines. I removed the new t-stat and did some more forum reading. I tested both it and the old one. Both opened up fully in a pot of heated water as soon as it started boiling. The tits on each opened up the same amount as ones I found in pics in the forum of 'good' thermostats.

At this time I figured I should verify the gauge before proceeding. I bought an IR temperature gun and tonight let the car warm up again.

Here are the temperatures I read with the gauge at the 212 F 'calibration' mark:

Sump: 210 F
Tank: 200 F
External thermostat housing: 195 F

I assume this means my gauge/sensor are more or less accurate. Again, my front cooler lines were cool. They were slightly warm for a few inches past the thermostat housing, about what you would expect from conduction from the housing, not from any hot oil flow through them.

So I'm looking for a sanity check and advice. I believe that I have either plugged hard lines or possibly a stuck-open pressure relief valve on the bottom of the t-stat housing. Note that my hard lines show no signs of damage (crushing). Is my thinking reasonable?

I briefly tried getting the relief valve cap off tonight and had no luck. The thermostat cap had come off surprisingly easily with a pipe wrench. My pipe wrench won't go around the bottom cap, and vice grips are just slipping off. Any pointers here? Or feel free to tell me that I'm wasting my time with the relief valve...

I've read the horror stories about trying the get the hard lines loose from either end without destroying everything and have seen the prices for new hard lines and thermostat housings and am dreading digging into that. Any tips for troubleshooting without pulling stuff apart? I read one thread where it was suggested that the t-stat element could be removed temporarily and the car ran to see if flow makes it to the front. Is this safe to do with the car warmed up first? I don't want to blow the cooler obviously.



Thanks for reading my rambling, and for any advice!

[Techno Duck]

If you haven't already, inspect the hard lines to make sure they haven't been crushed from poorly positioned lifting equipment.

[ppetion]

You mentioned they you replaced the tstat with a new one. If you are unable to remove the hard lines , how did you get to swap them ?
Am I missing something ?

[rbarton]

My cooler lines appear to not be crushed anywhere.

I replaced only the element and spring in the thermostat housing, not the entire housing. I was able to do this without removing from the car. Just removed the side cap with a pipe wrench.

[boyt911sc]

Originally Posted by rbarton

My cooler lines appear to not be crushed anywhere.

I replaced only the element and spring in the thermostat housing, not the entire housing. I was able to do this without removing from the car. Just removed the side cap with a pipe wrench.

Not until you could test and confirm that the slide valve of the auxiliary thermostat is opening @190°F and fully open @ 212°F, you are hoping everything is working fine. That is if you are lucky. However, you can not rely on luck all the time. Test and confirm for peace of mind.

Tony

[rbarton]

I tested the thermostat inserts in a pot of water heated on the stove. The wife loved this by the way. It began opening just as boiling started and quickly fully opened (212F). Both my old and the new one acted the same. Is this not a good test? Also, the inserts slide freely in and out of the bore, and I triple checked that they were installed correctly. From this, I believe my thermostat works correctly. Wrong?

Thanks

[uwanna]

How about you remove the flexible lines at the oil cooler radiator and check if you perhaps have a plugged up cooler. If the cooler is plugged it would not allow flow through through the pipes, the oil would just be static in the system. I really doubt the brass pipes would be plugged.

[rbarton]

I think that's a great idea uwanna. I saw where someone had carefully cut the nuts on the front flex lines with a Dremel to get them off without damaging the threads on the hard pipes. The flex lines are cheap. I can then pull the cooler, check it for plugging, and clean it up real well while I'm at it...

[RFP]

Originally Posted by rbarton

I think that's a great idea uwanna. I saw where someone had carefully cut the nuts on the front flex lines with a Dremel to get them off without damaging the threads on the hard pipes. The flex lines are cheap. I can then pull the cooler, check it for plugging, and clean it up real well while I'm at it...

If you do all this, be sure to replace the seal that surrounds the cooler assembly (unless this has already been done... recently). By the way, it's a b**ch getting the cooler reinstalled.

[JRSIII]

Before I went to the trouble of pulling the cooler, I sure would want to verify that the spring and pressure piston in the thermostat are installed and working properly. However, like you, I was unable to get the smaller cap off even with the thermostat off and in a bench vise. But I had no reason to suspect it wasn't working, so I decided just to leave well enough alone and just test the thermostat element. Had I been experiencing your symptoms, I might have tried to give it a bit more "persuasion".

Note I'm not sold on the idea of removing the element to test flow. With the element removed, the oil has an open path from the engine through the thermostat housing and back to the tank, so I don't see why the oil wouldn't just take the path of least resistance, as the pressure drop through this path has got to be less than through the long lines and cooler, if if the cooler isn't plugged.

[rbarton]

Good info all. Thanks.

My current plan:

1. Try harder to get the relief valve out to check. Anyone have any tips on grabbing hold of that cap?

2. Tackle the front cooler if #1 shows no issue.

[Jack Stands]

Could you undo the feed line to the cooler and see if you get oil flow to that point, then continue along the circuit to see if ou have a blockage somewhere in the system? It sure sounds like the oil isn't flowing, but I can't imagine one of the tubes or hoses getting blocked as they are of a fairly large diameter.

[proporsche]

Hi..i would just remove the thermostat and go from there...Start the engine a go for a drive.You be able to hear the oil traveling in the pipes.It makes funny sounds like glo glo glo..and of course feel the pipes carefully..

Ivan

[rbarton]

OK, so it's time for an update. Thanks again for all who've shared their ideas. Unfortunately I haven't resolved my problem yet. Here's where I'm at:

1. I removed the pressure relief valve from the thermostat housing. The piston was undamaged and moved freely in its bore. I did go ahead and put a new spring in and tried running the car again. Same thing. Car would get up to 215F or so as measured at the thermostat housing with an IR gun. The hard lines in the front fender remained cool.

2. I removed the front oil cooler. I did buy the wrench set from Pelican and am very glad I did. I had been hitting both ends of the flex lines with PB Blaster daily for over a week. I found that I was able to slightly tighten the flex lines where they attached to the hard lines and then loosen them up. The flex lines would not budge at the oil cooler connections in the same manner, so I removed the cooler with the flex lines attached. I ended up having to cut the nuts with a dremel and split them to get them off the oil cooler.

3. Now removed, I tried as best I could to test flow through the oil cooler. I blew it out with around 30psi air. Oil puked out the other end. It wasn't exactly immediate, and I had hopes that maybe I had just broken something free in there. I I then used the garden hose and got what appeared to be decent flow through it. I repeatedly sprayed in a bunch of WD40 to try to flush all the water out, and let the cooler drain. Repeated this and blew it out with air a couple times. I then ran some oil in and let it drain as well.

4. I then wanted to verify flow through the hard lines. It seem unlikely that they would be plugged, but I wanted to try everything I could think of while the cooler was off. First, my wife started the car while I was at the front fender. Oil started shooting out of the supply line within 5 seconds of starting the car. We shut it down quickly. I also again removed the thermostat element, left the plug out, and blew the return line back from the front with low pressure air. Oil puked out of the thermostat housing. I believe that I therefore verified that the hard lines were clear.

5. While the thermostat element was out, I again tested it by heating it in a pot of water heated on the stove. When I had done this previously, the tit had come out but I had not checked to make sure that it was not easy to just push back in. I wanted to repeat the test, making sure that the element was strong enough to overcome the spring pressure which tries to keep it closed while in operation. I went ahead and stuck both the old element and the new one in the pot of water. They both began to open at 180-185F, and opened to approximately 1/4 to 3/8". Both opened an equal amount and at the same rate. I pulled them out of the water and found that I was unable to push either back in by pushing as hard as I could against the granite counter top. I put the element back in the housing, again making sure that it moved freely in its bore to ensure that it wasn't hanging up somehow.

6. I reinstalled the oil cooler using new flex lines. I left the return hose free (not attached to the hard line). I wanted to verify oil flow through the cooler. It took perhaps a full minute for me to get oil flow ( I assumed it took a bit for the oil passages to fill up), and it was more of a weak stream/trickle than strong flow. Nothing like what I had seen previously out of the supply line. Hoping this was normal, I put everything back together. Started the car and again saw 215F at the thermostat housing before I shut the car down. The hard lines in the fenderwell stayed at ambient again, dammit.

So my current questions:

Should I have seen stronger flow out of the oil cooler? If it is partially plugged, is the oil following the path of least resistance and just returning through the thermostat housing instead of flowing up front? Or possibly the relief valve is even opening due to high pressure (blockage) in the cooler?

Am I missing anything? I'm kind of at a loss. I'm tempted to buy a new aftermarket oil cooler ($200 or so) and give it a shot. I hate to throw parts at problems and would like to have some confidence that it would fix my problem...

Thanks again!!

[Joe Bob]

Since the lines at the t-stat have been freshly removed, crack them open and run compressed air thru one and see if it is clear. My guess is the new t-stat is non functional.

[Jack Stands]

Sounds like you have some sort of a blockage or restriction in the cooler itself. I'd imagine the oil flow out of the cooler should be similar to that coming to the cooler. Perhaps you could try to connect the flexible lines together (bypassing the cooler itself and see if you get good flow through the lines.

[gomezoneill]

Post some photos of your oil line install around the tank. Since the engine was out for a rebuild (top end) maybe one of the rubber lines are pinched, kinked. Did you have this problem before the engine was out? If not,maybe your problem is related to the reinstall of the engine.

[rbarton]

To clarify, I have not taken any hard lines loose at the thermostat housing due to the pain I've read that can cause... I've only removed the caps off the housing with it still in place in the car. The only lines I've taken loose are up front at the cooler.

The oil lines all look good. At the tank, along the rocker, and up in the front wheelwell.

I think I'm going to try to source some M30 fittings locally and make up a "bypass loop" to take the place of the oil cooler as Jack suggested.

[Joe Bob]

One would assume that the t-stat has gotten hot enough to open? Do you have a thermal thermometer and read the temp of the t-stat?

[rbarton]

Yes, I'm reading the thermostat housing with a IR gun. Letting it get to 215F before shutting the car down each time I test. Have verified that the element itself opens at around 185 and that it slides freely in it's bore.