Hey, guys. This is my first post. My problem may have been covered before, but I've done a lot of searching and I haven't found anything quite like this yet.

I just got a '91 RS. History is largely unknown on this thing. Nice, clean car, but it's got a "salvage rebuild" title and a lot of changes have been made to it. It was at some point bought from a junkyard, presumably wrecked and looted for parts. I don't know what all has been replaced. It's got a new interior. Got a new trans, rearend is geared really low. Quite possibly 4.10's, but the speedometer is accurate. It seems most of the work was done right. The VIN says it had a 305, I think it still does but I haven't checked the casting number. Formerly TBI. It's been carbed. Edelbrock 1406, aftermarket intake, Mallory HEI. It sat for three years before I got it, didn't run so well at first but I did a lot of work to it this past weekend and it runs quite well now. I've just about ironed out all the bugs now except one.

The temp gauge works, but it's incredibly wrong. At first it didn't work at all, but I found that the green wire had come off the sender on the driver's side head. I put it back and it did at least register something as the car warmed up. It got just over 100, maybe 110. But I know it's a lot hotter than that. I put a 180 thermostat in it, and a mechanical gauge on the intake manifold. It runs at 210 with the AC on in heavy traffic, 195 on the highway. It seems this gauge is right about 100 degrees off. It moves when the mechanical gauge moves, and when I crank the car it pegs, so I know the gauge works. When I pull the wire it rests on the left side, when I ground the wire it goes all the way to the right. I tried replacing the sender today and it did nothing. Any ideas?

Thanks!

 

Welcome Aboard!

Get out your trusty ohmmeter. Disconnect the green lead at the temperature sender in the LH head. Check your other temperature gauge and read the resistance of the temperature sender to a good engine ground. The resistance should be close to that listed in the table:

 

Alright. I don't have an ohmmeter, but I'll see if I can get my hands on one this weekend and let you know what I find. Thanks!