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Sun Nov 08, 2009 6:57 am

I'm getting extremely hot temps in my bus and it's like 36 deg outside... I don't believe my DD gauge so I'm searching for answers. I been through the whole cooling system and checked out everything, and I mean EVERYTHING.

The crush washer on the spark plug is the only thing I haven't removed on my spark plugs. I hear that it is necessary to remove the washer, but why?
Does the little aluminum washer distribute an excessive amount of heat to the ring terminal on the DD?

I'm going to remove it today and see what reading I come up with.

Sun Nov 08, 2009 7:29 am

If the temps are high you might want to retard the timing a hair or adjust it slightly rich until you find the problem. Did you check the condition of the plugs for a lean indication.

Sun Nov 08, 2009 7:30 am

1975 Kombi wrote: If the temps are high you might want to retard the timing a hair until you find the problem.

did this... thanks for the tip though.

I just wanted to see if anyone else left the crush washer on the spark plug and had the same problems with high temps.

Sun Nov 08, 2009 7:44 am

The instructions say IIRC that the crush washer must be snipped off the spark plug. Why are you doing it otherwise?

Sun Nov 08, 2009 7:48 am

I think the crush washer helps keep the plug from un threading but it also decreases compression slightly.

Sun Nov 08, 2009 8:49 am

The crush washer will keep the spark plug from threading all the way in when used with the CHT sender also. The CHT sender is about the same thickness as the washer and can seal the spark plug to the head without the washer. You may have high temp readings because you have a leak at the spark plug with the CHT sender. Pull your plugs and look for black soot at the sealing surface. If you have the black soot, you will have higher CHT readings.

Sun Nov 08, 2009 10:53 am

X2: The sender IS the new crush washer, so why do you feel the need to have two?

Sun Nov 08, 2009 11:19 am

cut the crush washer off.

That said my suggestion is to borrow or buy an infared temperature gun to see if the sender is accurate. We have a VDO gauge and have the same issue where it reports high, I just haven't had the time to verify it with a temperature gun. My own belief is that CHT gauges are inhertently flawed by their nature however they do act a a warning when things go really wrong and that is the only reason we have ours. If everything is working right and the heads clear of debris, the doors open, air blowing out on both sides, what does it read at idle? Ours for example reads about 325F at idle and 350F at light cruise. I find it astronomically hard to believe that the temperature is only 25F degrees higher under cruise than at idle. If this is true then the VW engineers were miracle workers to get the air flow paths and volume near perfect for stock builds.

Sun Nov 08, 2009 12:53 pm

The VDO gauge is not temperature compensated.. In cold ambient temps it will read higher than actual temps, in hot weather it will read colder than the actual temps.

Smurf,
how high are your temps?? Also be aware that retarding timing can ELEVATE head temps due to increased EGT and the heat that is soaked back into the heads from that.

Sun Nov 08, 2009 6:12 pm

Jake Raby wrote: The VDO gauge is not temperature compensated.. In cold ambient temps it will read higher than actual temps, in hot weather it will read colder than the actual temps.

Smurf,
how high are your temps?? Also be aware that retarding timing can ELEVATE head temps due to increased EGT and the heat that is soaked back into the heads from that.

I'm reading like 390-420 deg driving flat roads at 50-60mph. I took off the washer and it was the same. No difference. If I'm climbing a slight hill it gets up to about 440+. I'm lost. I've tried everything but doing the air fuel mixture, cause I don't have a machine to test it on. I did a smell test with my nose, but other than that I can't tell what the reading are.

Sun Nov 08, 2009 6:20 pm

How do the plugs look. Black or brown. You might want to try that oil additive that is super slick. It might reduce some of the friction. How is the oil temp relative to the head temp?

Sun Nov 08, 2009 6:28 pm

My plugs don't really have color to them, and they kinda smell a little like gas too. But they are firing!

Sun Nov 08, 2009 7:11 pm

Smurf wrote: I'm lost. I've tried everything but doing the air fuel mixture, cause I don't have a machine to test it on.

Very easy to move the cog wheel in the A/F meter one cog to see what difference it makes. Just be sure to put a paint mark on the wheel so you know exactly where you started. A click counter clockwise makes it richer.

Sun Nov 08, 2009 7:29 pm

Smutf - you need to buy one of these and confirm that the gauge is correct. You may be making a harmless situation bad.

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=96451

Sun Nov 08, 2009 8:08 pm

Wildthings wrote: Smurf wrote: I'm lost. I've tried everything but doing the air fuel mixture, cause I don't have a machine to test it on.

Very easy to move the cog wheel in the A/F meter one cog to see what difference it makes. Just be sure to put a paint mark on the wheel so you know exactly where you started. A click counter clockwise makes it richer.

did this one already. but without a sniffer how would i tell if i'm actually doing anything?

Sun Nov 08, 2009 8:12 pm

Smurf wrote: Wildthings wrote: Smurf wrote: I'm lost. I've tried everything but doing the air fuel mixture, cause I don't have a machine to test it on.

Very easy to move the cog wheel in the A/F meter one cog to see what difference it makes. Just be sure to put a paint mark on the wheel so you know exactly where you started. A click counter clockwise makes it richer.

did this one already. but without a sniffer how would i tell if i'm actually doing anything?

If it changed your head temperature reading you would have accomplished something. If not move on to the next step, which might be calibrating your sensor as SGKent suggests.

Sun Nov 08, 2009 8:15 pm

Those lazer thermometers will only verify your reading at dile however, so you will have to do with that. Try to shoot it right at the sender to get as close as you can.

Mon Nov 09, 2009 6:56 am

The first step really needs to be to verify that the gauge is telling you the truth. Have you read and tried the troubleshooting directions in the DD manual? The DD has a lower sensitivity of about 150F. That means that accurate temperature readings start there. If an IR sensor is not available, can you put the thermocouple in some water with a thermometer and heat it up (150F+) to cross check the DD gauge? Was the gauge reading differently - say a week ago? What changed? Good grounds are critical in instrumentation and are so difficult to get and maintain in a vehicle.

From the DD website -
Gauge lights up, but does not read correctly:
Loose connection on sensor cable terminal - Reconnect cable wire.

Poor ground connection - Move ground to different location

Red and yellow wires in sensor cable are shorted -Check all splice connections and inspect cable for pinched or damaged insulation.

Temperature unit is not set correctly (F or C)- See “Setting temperature setup” in the manual.

Voltage or wiring problem in vehicle wiring harness - Check wiring harness for loose or damaged wires

Mon Nov 09, 2009 8:17 am

i would recommend moving your CHT sender to one of the head studs.

i was having the same issues. then i moved my sender.
now i don't have that problem anymore.

100% psychological. 100% effective.

Mon Nov 09, 2009 8:39 am

If he's using a DD, I think he's getting accurate readings.

Either a) he's getting exhaust leakage at his spark plug
or b) his head is really that hot.

Is the sender still circular? It it's oval then it needs to be replaced

I don't understand "my spark plugs don't really have color". Everything has a color. White? Gray? Brown? Black? Do they all look the same?