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Wedge The TR7 Temp issue -- finally, an answer

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sammyb

Luke Skywalker
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Well, it took my master mechanic buddy Adam to come over and diagnose everything in less than 5 minutes.

He took the old sending unit and the new one, tested them with a multimeter, dropped them in hot water, and tested them again.

The results: the old one -- shorted out (just wore out.) The new one -- built in reverse. It has more resistance as it gets hot! He basically said, if you leave it in there, as the car warms, the gauge will start moving down! (but not equal and opposite.)

So of the items I ordered from Victoria British, the sending unit was bad, as was the oil cap decal for my TR3 (and the "replacement" one they sent.)

Maybe I'm done with Vicky Brit!

Oh, and Adam said the reason the car won't idle well is that my carb base mounts are shot, and the carbs are pulling away under throttle!

If anyone has any extras, let me know! (I'll post in a separate thread if anyone has extras.)

Thanks!
Sam
 
Wow! A thing like that with new parts could cost you your sanity. I have had experience with VB and incorrect parts, a nuisance for sure but they did make it right. The bugaboo is the return shipping charges are often more than the part is worth. I would give them the benefit, but it's your call.
 
I'm glad you got the right answer! Back to the road again /ubbthreads/images/graemlins/driving.gif
 
Sam, I'm glad you finally got it sorted out, and it was simply an indication problem.
I don't want to get into vendor bashing, and Basil can delete this if he sees fit, but I, over the years, have found that there are certain items that I won't source from some places. You found one of them. Strange as it may seem, I've found that for items such as temp senders, oil pressure switches, etc., my local NAPA store has been pretty darn reliable.
Also, have you talked to British Parts Northwest? https://www.bpnorthwest.com/
Fairly close to you, and I've had good luck with them in the past. He has a temp sender listed for the TR7, OE Lucas, for $7.58.
https://www.bpnorthwest.com/.sc/ms/dd/109...pit%2CTR6%2CTR7
Jeff
 
Hello Sammy,
I have posted about temperature gauge problems on the Austin Healey forum and what I found out is that some earlier gauges work opposite to the way to what I am used to, namely shorting the sender cable to earth on the old system gives a zero reading (rather than max). Maybe this sender is for the earlier type of instrument?. And it is a case of mistaken identification of a spare part.

Alec
 
Hey Sammy,

Just my $0.02 worth. I had ordered replacement carb mounts from VB last fall, they lasted less than one tank of gas and both failed, they replaced them and the replacements lasted two tanks and failed. They finally gave up and refunded my $ (after a month and a half of me bugging them about it.) I found some suitable used originals on EBay for $6.00 each, however, over the Winter I am going to make my own from using teflon instead of rubber, I'll let you know how it goes, I think I'll have about $30.00 and a case of beer into them by the time I'm done with them.
 
Steve99--That stinks...I'm so sorry to hear that!!! Don't know how long it takes you to remove your carbs, but I just struggled for 90 minutes and still need to remove three bolts from the carbs to the mounts. There must be a trick I don't know about -- since I can't find a way to get a wrench on the lower inside nuts!

The thought of having to do this multiple times would make me depressed!
 
Hello Sammy,
I don't remember if I had any problems replacing the mounts on my daughters Dolomite, but I doubt if it took me 90 minutes for the whole job. Do you have or know about 'C' spanners, 90 degree open ended spanners or crows foot sockets, they certainly come in useful when you need them.

Alec
 
Your right Sammy, The lower, inside studs are just a peach. One of those applications that Id really like to meat up with the engineer that designed this and let hime or her fix it. I have not found any easy method for removing and assembling those two, Just a wrench, time, and patients. I did however find it very relieving to my back if I put the car up on stands to do this.
 
Gee...after hearing all this about the carbs, sure glad mine's fuel injected /ubbthreads/images/graemlins/nopity.gif /ubbthreads/images/graemlins/driving.gif

However, I can add that the engineer that adapted the Bosch Jet-tronics system for the Brits should be shot./ubbthreads/images/graemlins/devilgrin.gif
 
Ahh, that's what I need -- the C-wrenches. I don't have any, but my good friend Bret(a mechanic) does -- and he's out of town for three weeks ...hmmm....;) Maybe a run down to his shop and loot through his tool box, and replace them before he gets back!
 
Hey Sammy,

Technical point. It is absolutely not possible for that to be a manufacturing error or some such.
There are two types of thermister...1 type increases resistance with increase in temperature. The other decreases resistance with increase in temperature.
It would be inconceivable for them to get "Mixed Up" (I would doubt that both would exist with any proximity anywhere these things are used.
As Alec said; they got mixed up and gave you the wrong part.

Mike
 
Sure sounds like Sammy got a sending unit from and early TR with positive earth, between them and MGA's and early "B"s I sure had to stand around and scratch my head alot. Wayne
 
The box was the correct part number, and it looks IDENTICAL to the one I took out, but alas, it's the reverse in resistance.
 
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