Where does the temp gauge point?

[Clan]

Originally Posted by macplaxton

I understand what you mean, but did you not mean to write "high temperature"?

yes of course i did :-) oops

[Clan]

Originally Posted by Joe Harding

Good information, thanks. So in your opinion, what would be the most likely reason for a low temp reading on a 1987 340? I have swopped the thermostat with no success and checked opening temps (about 90 deg) Do the engine temp transducers go high resistance?

Or is there another possibility that with a new radiator, fully flushed system with a good strength antifreeze I simply have too efficient a cooling system? I mention this because in hot weather and standing traffic, the fan does sometimes come on and the temp gauge rise above mid-position.

The fact that the temp gauge goes over N in traffic is good , it shows the gauge is capable of going up to a normal higher position so i would look at the thermostat again get the warmest you can find over 90 C perhaps a 92 C . The sensors can go high resistance with age yes , but more likely with the Smiths than the VDO which you have . .
The radiator can be twice as big and the system should still stay the same temperature , the thermostat controls the actual temperature .

[Clan]

Originally Posted by foggyjames

Is it a quick job to demonstrate the repair procedure? If so, I'll bring my spare one down with me when I drop the amp off, if you'd be kind enough to show me the ropes?

cheers

James

Hello James ,
Actualy you just need to grind off the rolled edge that holds the plastic top in , a dremel type tool is ideal ,then clean the metal parts inside and the spring , you may see some green corrosion . Then use some araldite to bond the top in again , the internal spring may press up so some sort of light clamp may help to keep it together until the araldite bonds . It worked on two of my 30 year old senders .

[foggyjames]

Many thanks - I'll certainly give that a go! I might try a variable resistor first to make sure that the gauge is still working...

cheers

James

[Joe Harding]

Originally Posted by Clan

The fact that the temp gauge goes over N in traffic is good , it shows the gauge is capable of going up to a normal higher position so i would look at the thermostat again get the warmest you can find over 90 C perhaps a 92 C . The sensors can go high resistance with age yes , but more likely with the Smiths than the VDO which you have . .
The radiator can be twice as big and the system should still stay the same temperature , the thermostat controls the actual temperature .

Yes, now you say it, it is obvious. Thankyou. Do you know where a thermostat with a higher opening temp can be got?

[macplaxton]

Originally Posted by Joe Harding

Do you know where a thermostat with a higher opening temp can be got?

Can't help directly on this one, but can point you in the right direction...

Volvo 3293501 - 92C Thermostat




Most aftermarket supplier catalogues only list 89C as the highest. Volvo listed them up to 92C. The one I got was from the DAF Club Nederland, and it happened to be made by Wahler (Gustav Wahler GmbH).

Wahler have them in 83C, 86C, 89C, 92C temps. Their part numbering is self-explanatory: 3029.83, 3029.86, 3029.89, 3029.92.

[macplaxton]

Originally Posted by Clan

Hello James ,
Actualy you just need to grind off the rolled edge that holds the plastic top in , a dremel type tool is ideal ,then clean the metal parts inside and the spring , you may see some green corrosion . Then use some araldite to bond the top in again , the internal spring may press up so some sort of light clamp may help to keep it together until the araldite bonds . It worked on two of my 30 year old senders .

I can't explain it in words as good as Clan, so instead here are some pics of my spare old two-tag Smiths one, James (that I was playing with yesterday )

Removed the peined-over edge:

Remove terminal block (note screw and rectangular hole):

Remove O-ring:

Terminal with blue insulation sleeve is the large one for the gauge needle and presses up against the terminal in the rectangular hole. Terminal with the contact point is for the warning light - it is calibrated by the screw in the plastic section (connected to the small terminal) which is sealed.

Looking at the condition of the terminals, the warning light probably still worked, but the dullness of the other terminal (like an old penny), was such that the gauge needle didn't lift to the right at all.

Refitting is the reversal of removal (in Haynes-speak )

For reference, the above part is Volvo 3285410 / Smiths TTS 1103/00

[foggyjames]

Outstanding! Presumably either mechanical or chemical cleaning of that contact should bring it back to life?

Dare I ask where you found the sender in the end? I've found your old thread on V3M, but drawn a blank on new parts.

cheers

James

[Chris_C]

I imagine that the terminal could be plated with something, so I'd be super careful with mechanical cleaning and it doesn't look like you could get a fibreglass pencil in there. I'd be tempted to start with contact cleaner and work up from that chemically (IPA, acetone etc maybe?).

[macplaxton]

I'd just fire in with some abrasive on the NON contact point type terminal, that's the one with the blue insulating sleeve. I'll give it a go sometime.

The contact point one I'd be careful with, because if you take any material off it, you'll probably have to adjust the calibration screw.

As mentioned, I'm in the DCN, which has more than paid for itself over the years for those elusive parts, even if sometimes they aren't cheap and can be eye-wateringly expensive.