Temp gauge question
 

I am installing a 89 motor into a 79 truck (both chevy), can i use the 89 temp sending unit to operate my 79 water temp gauge (will it read correctly) or do i need to use the 79 sender unit the gauge was made for. These are all stock parts. If i need to use the 79 unit is putting in the water pump good enough. 89 is 3/8 inch & 79 is 1/2 inch & there is a 1/2 inch plug in the water pump.
Thanks
Andy

Re: Temp gauge question
 

Well, after rewording my search 3 times, I see that I need to use the OE temp sender in the newer engine due to different resistant (ohms) values of the senders. So now my only question would be, is the water pump location a proper spot to install it?
Thanks
Andy

Re: Temp gauge question
 

According to some of the old parts catalogs I have, there are a couple sending units that have the correct temp vs. resistance curve to work with the stock 79 gauge. One is GM #8993106 and has 1/2" pipe thread, the other is GM #8993146 and has 3/8" pipe thread.

So you should be able to use one of those #8993146 (or equivalent) sending units in the stock location in the 89 engine. I wouldn't recommend placing the temp sending unit in the water pump since that is on the "cold side" of the system ... in other words, the coolant that is flowing through the water pump has already passed through the radiator and will be cooler than readings you'll get at either the cylinder head or intake.

Re: Temp gauge question
 

Another option is get a later year gauge to install in your cluster. Don't think the gauges changed physically even though they changed expected resistance two or three times.

Some aftermarket intakes have a 1/2 plug about where the water exits the heads just before the t-stat.

Not optimal but you could get a t-stat housing with a 1/2 fitting and put the sender there. Might not pickup a stuck shut t-stat until it was too late.

Re: Temp gauge question
 

Ray
Thanks for the part #'s and your input about using the water pump location as not a good spot. I'll check with my parts guy this week.

Dead Parrots
I will give the engine a through look this week after I get it up on the engine stand and also check out that replacing the gauge option.

Many thanks for the quick response to you both

Andy