Low oil temp, and low boost? More gauge-related questions!

Alex · July 31, 2009, 08:32:50 PM

I'm not sure someone as OCD as me should have gauges in their car, but it makes sense to check this!

Oil temperature seems to rest at 62-65C on the motorway, rising to about 80 when it's stopped in traffic. Is this too low? I would expect it to be at about 90, I'm sure that's roughly how hot the Passat runs (according to my Dashdaq). It's possible when the sump plug was swapped for the sender that some oil got onto the contacts, so I'll try cleaning them tomorrow just in case.

Boost readings are slightly lower than I'd expect as well - about 0.75 BAR under most heavy throttling, rising to about 8.5 at the top of the rev range. It's got a full blend, toothed belts, GT inlet and still has wedges. I'm sure with that spec I should be making near 1 BAR, or is that optimistic?

Alex · July 31, 2009, 08:44:03 PM

Oh yeah, I've got an oil cooler with a thermostat. Could be stuck open I guess?

Alexiskayak_7 · July 31, 2009, 09:54:17 PM

I haven't got an oil cooler..
The readings are: 92-95 on motorway (off boost) and 95-110 on traffic
The oil temp in too low...

For the boost now... I have a stock g lader and i have only a panel filter in the air box and i read 0,65-0,7 on full boost...
I suspect that something is going wrong with the gauges...

Alex · August 01, 2009, 04:08:01 PM

Damn, I wonder which it is. AFAIK my oil cooler should be keeping it under 95, but obviously it's far too cold. The sender plug and wiring does have very good airflow across it, that wouldn't affect anything would it?

supercharged spaniel · August 01, 2009, 07:25:19 PM

Mate...i would have worse OCD if i had gauges..hence why i don't ha ha.

Alexiskayak_7 · August 03, 2009, 10:11:06 PM

Alex, if you unbolt the oil supply hose and start the engine when it's cold and if the oil flushes the thermostat is stuck open...

Alex · August 03, 2009, 10:20:27 PM

But, if the thermostat was stuck open surely that would mean the car would take longer to warm up but would eventually get up to temperature? I gave it some stick, and it was still reading low.

hardchargin40 · August 07, 2009, 08:39:37 AM

Could be gauge related. But to be sure, just disconnect the oil cooler and sandwich plate and try it with just internal oil. If your temps are normal, suspect thermostat on oil cooler setup. BTW how large is your oil cooler?

Also, boost wise, make sure you haven't got any tiny boost leaks, say around the intercooler (or pinprick leak in intercooler itself), charger outlet pipe to intercooler always a good un. Also leak from ISV to plastic boost pipe hose - where it joins the plastic boost pipe (ive had mine crack around there before).

Also, check that you boost return valve is fully closing on full throttle.

Alex · August 07, 2009, 08:59:35 AM

It's a 13 row 235mm cooler, so pretty small really. I'm going to drop into the workshop tomorrow and have a look at it. I'll check the boost pipes while I'm there