911Jetta

Update: I've fixed the problem - both the oil thermostat insert and oil ballast resistor were bad. Enjoy the thread below as I reached new highs and lows in my efforts to diagnose and fix the problem myself. I also gathered TONS of useful information through a through RL search.

Just the other day my oil temp jumped from its usual spot on the dial, 8:30-9 o’ clock, to 10 o’clock. As an extra precaution, I opened the engine lid and stuck a big floor fan in the bay to help cool things down when I got home.

Ok, looks like I have a thermostat issue to solve? I’ve never touched any of the parts involved (except the oil drain plug) and the systems mostly just work with me being oblivious to it all (fans turning on and off)…now it’s time to learn lots of NEW stuff, and prove my metal...hope I’m not crying by the end of this…

I really need your help on this one. I’m hoping to drive up to VIR in the car this weekend and watch the races. I hope to order parts tonight (extra parts if necessary) to hopefully solve the problem?

What I know:
• Engine oil temp normally runs below 9 o’ clock
• Changed the oil about 300 miles ago, could I have tweaked the thermostat while opening the oil drain plug?
• #2 fuse in the trunk is fine
• Switched the R04 and R14 relays (have not turned on the car yet)
• Still very confused as to how to up do a relay jump? Would any decent auto parts store be able to create one for me?
• I haven’t checked the front fender temp (to see it if was hot or not)
• The temp. did not climb past the 248 mark – No warning light also, so HIGH speed fan is working!

What I’ve done:
• In combing over tons to RL threads I’ve come to the conclusion that the low speed fan is not coming on and I need a new oil cooler ballast resistor AND (maybe) RO4 relay? I know it could also be the thermostat or a larger problem with the oil cooler fan, but this seems like a good place to start.
• Parts ordered overnight (resistor and relay)

What I’m planning on doing next:
• This afternoon will be the first time I can drive the car again (assuming it’s safe to get it up to temperature? I’m pretty sure the temp will go back up to 10’o clock again).
• I’ll check the front fender for heat (assuming it will be cold/warm).
• Check to see if the switched relays (RO4 and R14) effect the A/C fan operation? Switched relays, and no high speed A/C fan movement means oil cooler relay is bad? I’m assuming the relay jumper trick allows for the same thing to happen, but A/C will automatically work on low speed instead?

I’m in no-man’s-land right now, so thanks in advance for any additional support or help?! As a LAST resort...will EASY driving (25 miles) to my shop be ok?

As a side note: Thanks dfinnegon for the very helpful threads/post you have created on this subject!

Sultan

Same thing happened to me last fall, it was running at 10 o'clock (nearing red). I'm a mechanical moron so I didn't (don't) have the "know how to fix" cars so I took it to the shop after I checked that the front fender was ice cold. It was the thermostat I believe, it was replaced and now it runs no more then 9 o'clock.

Not sure if that helps you any more, or maybe provides some reassurance.

PS - nice colour on your 964 ! LOL

axl911

The next time you drive, the thermostats will probably work again. This is how mine failed. It failed intermittently before I replaced it.

Just replace the thermostat on my 993 when it went to 8 o'clock and not opened up. If yours is a later 964 model then you can just change the innards.

Change it now, oil is the life and blood of this car. My old 964 thermostat failed and the car got up to 10PM but not red. Shortly after, my valve guide went and went from consuming 1qt per 1000 miles to 1qt per 400.

911Jetta

Good info.

I know, this is oil temp we are talking about here! Hate the thought of seeing 10 o' clock again...

Just switched R04 and R14 relays. AC blower fan -inside car and front driver's side wheel housing fan- worked on full high (engine off, is that correct?).

Not going to try jumpers at this point, relays seem to be fine.

So I'm waiting for the oil cooler ballast resistor to show up (tomorrow) and hope I don't see 9 o' clock again after the install...otherwise I'm booking it in next week.

I have to do one more short drive this afternoon (picking up daughter, so a must do drive), will feel the fender when I get home, and practice taking the wheel housing panel off to see what's going on inside?

Pleasure/pain...I love this car.

911Jetta

snasrulla,
Thanks for your comments. You were smart enough to check the fender!
Love the wheel style on your car, perfect stance also!

911Jetta

Picked my daughter up, 10 mile drive...kept the revs loooowwww, painful cruised at <3000. Had to upshift at one point, less than 2000 revs on the clock. Anyway, I was thankful for the low engine-stress trip.

Driving like this, I only saw 9-9:15 on the gauge. So does that prove that I could drive it like this, to watch the races this weekend (easy, no traffic, flat 50miler)? That's a last resort option I'm holding on the side if the ballast resistor doesn't fix things...

Ok, I pulled the cover to expose oil cooler...first of all I see weeping from the oil lines into the oil cooler. There is oily grit at the top of the fittings on the cooler (see picture). Obviously tightening it would be good, but are these fitting tricky – should I leave them alone, to prevent even greater leaks from occurring from starting?

Now that the wheel housing panel has been removed I can see where the ballast resister goes…or at least match it to the descriptions from some printed posts. Ballast resistor comes tomorrow.

911Jetta

Sorry for all the posts to my own thread...just working through the problem.

So at the end of the day a couple things were bothering me...

The front fender didn't feel too after driving...does a cool fender mean that no oil was flowing through the cooler (@ 9 o'clock drive temp.), the thermostat remained closed?

Does a working low-speed fan create heat in the fender...by (the blowing fan) dissipating heat?

Now I'm confused as to whether I need a oil cooler temp. sensor (and)/or ballast resistor? Looks like the jumper test will decide...finally figured out how to make/test with a jumper?!

Pulled the R04 relay, jumped pins 30 an 87c - nothing, so no low speed operation, 30 and 87 works. According to past posts on the subject...the ballast resistor is gone. (Also tested the A/C relay, only high speed fan works also)

I'm done for the night...I had previously only ordered a new ballast resistor (and extra R04 relay), nothing for the thermostat. Hope that's enough to fix things?

Duck

If you are getting oil to oil cooler, probably then the resistor. I guess I wanted some control over the high speed fan, so I did what was done in the below thread and added a switch:

https://rennlist.com/forums/showthre...ferrerid=48310

Some people do not like cutting wires, but I have been very happy with this. If needed quickly, the wire can be cut and you will always have high speed fan until a switch is installed.

Again, this is not for everyone.

911Jetta

Thanks Duck,
I saw that post during my RL search stage of this process. Given that I've now successfully made a relay jumper, I now have a little more courage do install/create a override switch (I like the on/off light switch idea - instead of watching the gauge drop or listening for fans...). One project at a time though...

Given what I've described in my rambling posts above...

-Would a Hammer tool give me the answer right away, would it point to either the Thermostat or a resistor? I ask because I'm ignoring the thermostat, and focusing on the oil cooler...just wondering if the Hammer would speak the truth in one minute...

-I'm really feeling good about my relay jumper test, as it proved my low speed fan wasn't working. Nervous about that but feeling cautiously optimist at the same time...

-In the picture above (oil cooler fittings), what's the correct way to tighten things up? Hold the bottom nut, and twist the top nut as shown? Or leave it alone so I don't create another, bigger problem?

-Any ballast resistor install suggestions would be helpful.

Thanks for hearing me out...

elbeee964

The right fender should be noticeably warmer than the left after a drive that's opened the thermostat.
[Mental burp: huh, never thought of it before, but I guess that makes the front right fender one big, ol' engine radiator surface, itself!]

Anyway, right fender not warmer than the other?
That'd be a BIG sign of a stuck-closed thermostat or crushed oil transfer tube.
More, here.

FWIW, while warming up, my temp gauge goes a little past the 8 o'clock line, and about a 1/2 mile after that quite noticeably drops back to just below the 8 o'clock line. This I take is my thermostat having opened up circulation to the right fender radiator. Before that, the oil's just making the tank-to-engine-to-tank loop.

jimq

why are you worried about the temp being at 9? Mine stays between 9-10 all the time in the summer around here especially in traffic. My thermostat works fine and my fans blow. The oil thermostat wont open until its about at the 9 position. The high speed fan wont come on unless its above 10 or so.

911Jetta

9 is fine...but then all of a sudden the last two drives I saw 10 (during easy, low traffic driving). That's never happened before, plus I've always been able to see a temp. drop after the thermostat opens up. Now it just steadily creeps up to 9+, 10 if pushing.

The last drive I took, I babied it (2 to 3K revs) and came home with the gauge at 9:15+ (not close to 10). I was afraid to rev it to more normal levels (4-5.5K) as I didn't want to build up heat in the engine. I'm pretty sure I would have seen 10 if driven with normal revs? I'm hoping the relay jumper test proves the low speed fan wasn't coming on, and that will fix it.

Thanks for asking the question, believe me I don't want to create any more problems for myself than necessary (I almost did that once when I almost needlessly replaced my fuel filter), the car is basically running 1 o' clock higher.

Sorry for all the "thinking out loud", it all comes down to my desire to keep this car on the road...

911Jetta

That's the one thing in the back of my mind last night...was the fender warm or not? After that drive I had to unload my daughter, etc. so it took me 10+ minutes to get back to the car...had the fender cooled off by then?

That's when I decided to do the relay jumper test. I felt better after concluding the low speed fan wasn't working. Hoping that was my sole problem?

Still have the thermostat monkey on my back though...

race911

When the thermostat opens, and lets oil flow to the cooler, the fender warms up. That's a given. Maybe in Phoenix in the summertime you can't notice, but with your shrouding off it's easy enough to try to touch the cooler.

That said, the fan up there doesn't do a whole lot outside of miserable, commute-from-hell, stop-and-go traffic. I ran my '92 C4 without the fan for several years (to not restrict airflow through there when I was at the track). No noticeable difference ever when street driven. I'd estimate that even at 40-50mph you've got more airflow through there than any fan can provide.

I'll even confuse things further. Consider any 3.6 that's put in a torsion bar car. The three I've done, a big B&B cooler goes in the nose. No fan. Still no problem for street driving. Now I am talking about a moderate Bay Area climate; it still gets 100+ out in the East Bay sometimes.

tbennett017

You can try to run the A/C for a few minutes. This forces both cooling fans on, and will result in airflow over the oil cooler in traffic.

I installed a switch on line 16 (check me on that) which fools the CCU into thinking that the ballast resister has failed, which forces the oil cooler fan into high speed mode. I only use it on hot days in traffic, but it keeps the oil below 9:00 all the time.