I've ben searching & reading posts about temp senders. The guage on my 65 L78 indicates 170 when at operating temp. in my driveway, engine running, I have about 190 & rising with my infared gun, so the guage looks to be 20 degrees off. the sender says "made in USA" on it.

Seeing some had luck with AutoZone procured senders ($6) I picked one up. (Made in China). I removed the existing unit and compared them. The threads looked the same but there were more threads on the new unit. When installing it, it threads into the manifold about a quarter of the way-maybe more-and gets tough to turn. (I was not using teflon tape) reading about guys who crack intakes threading these in too far scared me and I backed it out & put the old one back. Should I try to crank the new one back in or just figure an indicated 170 is actually 185-190 and forget it?

Dan

 

I could not get my sender out....really old but worked great with original gauge...put in new gauge and the new gauge reads 150 to 170 at 190 with gun....I just live with it......did not want to damage my l-79 intake....


Jack

 

Thanks Jack, mine came out easy enough, it had no teflon on it but the threads were turning green, Brass and aluminum together set up corrosion, maybe its better I R&R'd it and it will work better now. I was waiting for a reply before I went out to fire her up for a leak test and to verify operation. Cannot imagine a $6 chinese sender is going to work better than what is in there now.

Dan

 

Here's one of my threads from 2010 if it helps. I didn't notice any difference in the way the new and old went into the intake though.

http://forums.corvetteforum.com/c1-a...ght=bwd+sender

 

I read that thread earlier, thanks. I have the Autozone TU5 and find it does not want to thread into my aluminum L78 intake past say 8 turns without horsing it, which I'm afraid to do-but I'm curious if it will read better.

Dan

 

Dan:

Your temperature gage reads the resistance of the sender and the incoming wire to the gage. It translates this reading into a temperature. The point is that the sender could be bad, or the resistance in the incoming wire could be high due to corrosion at the terminals/connections.

In my case, the gage currently reads about 20 degrees low due to corrosion in the incoming wire at the firewall block. It happened over time, and I have just lived with it. I have seen the gradual deterioration, and have verified the various temperatures using a Fluke IR gun. You may have a similar issue.

The best thing you can/should do to get an accurate reading at your gage (assuming the gage is working correctly) is to measure the resistance of the sending unit(s) only at a known temperature (say 180 F) and compare it to AC DELCO published tables. This information should be in the archives, or we can provide it. You can do this off the car in a hot water bath, or do it on the car and use an IR gun to get the corresponding engine temperature. This will tell you whether the sending unit is correct or not.

Also measure the resistance between the sending unit wire and the temperature gage. It should be essentialy zero (0) ohms. If it doesn't, you have found at least one of the problems....corrosion in the firewall junction box.

Larry

 

Larry: Much appreciated. I will do that.

Dan