Symptom Solution: Warm Up Regulator Replacement Project
 

The Warm Up Regulator Replacement Project on my 83 911SC is over and I did not turn myself into a gas soaked Tiki tourch. Which is suprizing considering I am not mechanically inclined.

This morning I finally got to test my WUR replacement and here are the results.

Symptom #1:
Bouncing Idle at warm up (starting with just a slow bounce then getting higher and lower until the engine goes from racing to stalling). This is also referred to as Idle Surge I believe. This was corrected instantly with the rebuilt WUR. As soon the engine turns over (cold start) you can tell the difference. The idle surges (bounces) twice by about 200 rpm and is ready to go, this is a difference between the old one to two minutes at 60 degrees ambient air temp and the new three to five seconds of fluctuation before settling.

Symptom #2:
Engine temperature creeps up uncontrollably.

In my case the initial warm up points were all met. At the end of the white operating temperature indicator the idle dropped from around 1,200 rpm to a solid 950 rpm which is normal and the temperature at the sump plate (laser thermometer) was within ten degrees of the (somewhat subjective) lines on the dash gauge. When I first picked up the car a year ago the temperature on my trips to work never exceeded 49% of the gauge. When the WUR symptom of a bouncing idle got worse (lasting longer despite warmer temperatures outside), the temperature shot up to 75% of the gauge for the 12 mile drive in medium traffic, regardless of removing the front marker light.

This morning, the temperature never exceeded 51% and I actually sat with the car running in the parking lot for five minutes and it never budged. It’s still a tiny bit high, but what a world of difference it made. The minor temperature difference could be how dirty my O2 sensor is (but that’s a different post all together).

The rebuilt unit I received cost $230 with the core charge. It took an hour to replace for a guy whose mechanical ability is only slightly above a retarded monkey. The advice given here in the group is great and the job is pretty darn simple looking back. The only special tools one needs (for an 83- 3.0 not sure about other models) is a socket with a 5 MM allen wrench end, cost me $14 for a full set 2-14MM of the Craftsmen variety (probably $5 at Harbor Freight).

You maybe tempted to buy the large “T” bar jobbies with a big grip handle, Don’t bother it actually makes the job harder because you have to remove the heater fan, if you unhook all the ducts and then push the fan up there is enough clearance to get a ratchet socket and extension in to reach the second allen bolt (hardest part of the job)..

I let my car sit until I could place my hand on the engine (about three hours) before starting. When I removed the fuel lines less then three drops of gas came out (Thank you John Walkers Workshop and DavErb for your sage newsgroup advice, I was pretty sure there was going to be a fiery explosion if I messed with the fuel lines, but that’s not the case if you let the car sit over night).


Now on to some points of intrest,
So there are a few threads out there indicating that The WUR does not affect the operating temperature beyond initial warm up. I beg to differ; I have just replaced mine (with no other alteration) and watched the constant run temperature drop by about 25%. I’m of the opinion that this is a result of now proper fuel regulation of Rich and Lean states. Before this project (months ago) I was able to reduce the operating temp by a few degrees by changing out the old the O2 sensor (again Rich/Lean) so I’m seeing a defendable trend -anything that regulates R/L can be a culprate of your hot running car- don't rule it out.

The long and the short. If you’re having Cold Start, Bouncing Idle at warm up and Hot Running issues. Check for vacume leaks, then the Warm up regulator, it’s a do it yourself replacement with minimal expenditure (less then $200 investment total if you return the core). If nothing else you will kill off at least one other issue and is thus worth it regardless. In my case it hit three at the same time.

Drawback/risk: I think I bent a rusty fuel line. will update on that later.

______
Akira28
1983-911SC 3.0
1984-944 NA

Glad it worked out for you. That fluctuating idle speed is usually referred to (at least on this BB) as "hunting".
It is most often a symptom of a mixture that is too rich, which can be caused by an out of spec WUR.

Since it usually means too rich, I'm surprised that on a hot day, when the idle is hunting and the mix probably too rich, your temp gauge went up considerably. A rich mix helps keep temps down; too lean often results in high engine temps.

A check of the O2 sensor is probably in order.

You likely should have the CO reset. This will ensure you are getting the right A/F ratio. It might be that the Lambda system is trying to correct for a out of spec CO which might be the bit of hunting you still have.

I like the idea of a new O2.

This should get you temps where they belong.

Lean is hot, rich is cool. A plugged Catalyst it hot...