BoostBuggy

In my continuing sage of this 86 951 I might be having a coolant temp issue. The reason I say "Might" is relative to the dash water temp gauge and whether it's accurate.

The water temp gauge shows my typical running temp at the first hash mark. Even last weekend when it got up to 100 degrees here I couldn't get the running tempt to go more than maybe a needle's width over the first mark. Even pulling the the fuse for one of the fans will barely nungh the temp higher.

the reason this concerns me is the car is still running way rich. As I understand it, if the DME thinks the engine is running under temp it will richen the mixture. Which could explain my running rich issue.

Is there any way of checking the engine temp other than via the dash gauge? i.e. how to I confirm the dash gauge is accurate and if it isn't what are the options?

BTW, it has a new water pump, new thermostat, etc. So those parts shouldn't be the issue. And FWIW, changing them did not change the running temp as it was the same prior to the new waterpump et al.

TIA

Michael

Tom M'Guinn

The DME and the gauge use different sensors. Your gauge sensor could be accurate and fine, but if your DME sensor is bad it can richen the mixture. Test the DME temp sensor to confirm it is working. You can also test the gauge sensor the same way. If the gauge is off and the motor is really overheating, you'd probably have more obvious syptoms, but you can also use a point and shoot thermometer on the radiator to see if it's super hot. I'd start by testing the sensors. See procedures to test the sensors at clark's linked below.

http://www.clarks-garage.com/shop-ma...9.htm#dme-temp

I believe I gave you a list of tests for the rich condition -- though my memory is not great -- have you tried them?

BoostBuggy

Thx Tom.

I didn't test the DME temp sensor but I did replace it with a new one (fwiw). Seems I will need to test this (new) sensor to see if it's working correctly. I'll give this a shot and let ya know...

LUCKY DAVE

The only fool proof way is to directly measure the outlet water temp with a high quality IR thermometer like us large boat guys do with our diesels. We never believe what temperature gauges say. For example, the mechanical gauges directly on my (twin V-12) main engines, the electric gauges on the bridge, the repeaters on the fly bridge and the ones in the tuna tower all read differently.
Ir gauges are useful for a zillion automotive measurements, not just water temp. Read the header temps on the dyno to compare cylinder to cylinder BMEP for example. Or like we do on marine diesels
to check injector function underway.
Buy a good one like a fluke, not something from Radio Shock.

Tom M'Guinn

Looking at the picture you posted in your other thread, are you sure the FPR at the back of the fuel rail is getting a clean vacuum signal? A good vacuum signal is critical to the correct fuel pressure, and I can't actually see where your FPR is picking up vacuum. It should get it from the banjo bolt in the intake just a few inches away, but yours appears to route up to the firewall?

BoostBuggy

The entire system was pressure checked for any possible vacuum leaks recently. There were leaks at the ICV (now replaced) and the wastegate (will be replaced with rebuilt turbo in about 1.5 wks) The FPR certainly should be getting a clean vacuum signal. It is getting it's vacuum off the banjo bolt in the intake manifold.

@Lucky Dave - Can you suggest a good reasonable IR thermometer? I'm assuming you're not thinking of something I might find at Harbor Freight, correct?

LUCKY DAVE

Mr Buggy, I own a Fluke brand, it's on the boat so I can't tell you the model number. Fluke makes top of the line electric test equipment, and is the brand most pro electricians use. Any electric supply house will carry them, so will Grainger.
I would also trust one from Ideal, it will be a little cheaper than Fluke. If you really want the Rolls Royce of IR thermometers, buy one from Omega, but be ready to pay $1000+.
In any case, be prepared to spend a hundy or two for a good one.
Harbor Fright or similar junk is not what you want.