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Temp guage not reading right..

J

josh89xj

NAXJA Forum User
Location
Minnesota
On my 89 xj I have a ongoing issue, I recently replaced the motor with a 87 xj 4.0. everything works great! Except the temp guage, I thermoed the engine and the coolant temp was 195 at running temp. But my guage reads 230 deg. I replaced the guage inside 2 times both are good but same problem,then replaced the sender on the cylinder head with 3 senders all did the same thing even tried a different sender and that just didnt work. Checked the grounds all ok what the hell else can it be???
 
check the resistens(sp)from all the wires.
Mine did it and i had to remove the head and blow out the sender hole it was full of black crud.
 
could it be napa just has wrong specs and its the part thats not right but not bad?Im lost..wife drives my jeep sometimes and although it reads its not reading the correct temp so she would never know shes overheating it.Its driving me nutz
 
I'm having a very similar problem. I absolutely *KNOW* my engine is running at the right temp, and there is no air bubble at the sender, but the gauge reads high ... almost to the redline.

I did a gauge cluster swap. Everything works perfectly except for the temp gauge. The only thing I can think of is that I have to try a different sender for a different year vehicle.
 
I tried that already,i tried 3 different senders,from napa. 2 didnt work at all but the 3rd does the same thing.Im going to try to change out the block sender too and try the sender from chrysler,those are all i can think of this is wierd..
 
Tested it last night w/ laser temp and it is in fact at 195-205. Why does the guage read 240? I replaced the guage and all senders.WTF!!!
 
corroded wire causing the resistance to be wrong? Did you clean the connector going into the back of the guage cluster?
Do you have the old gauge that you replaced? I would temporarily wire it it to 12V and the sender using jumper wires. If it reads correctly then you've got an issue in the wiring harness. Probably easiest to run a new wire and patch it in at the connector at the gauge clutser.
 
No, Tried a new wire direct from the sender to guage,still not working right.Also tried takeing out sender and ran some stiff cable down there to check for any blockage,none.Stupmed again!!! Im going to try a flush and fill in the coolant(kind of a waste) but worth a try.Im going to try a flush additive to clean it all out.So thats my next step for this weekend i think so well see.If that does not work my last idea is go to dealer to get new sender,maybe napas sender is just not made correctly.Ill keep ya posted.
 
perhaps it's possible that the voltage going into the guage isn't proper. Since it's a resistnace measurement then the input voltage would also cause the gauge to be off. When you jumpered wires directly to it did you run a 12V wire to it directly or was it in your guage cluster?
 
you said you swapped in a new long block, did it come with a temp sender? wonder if different year models have different senders and gauges that are not compatable with other years?
 
My 89 Limited gauge was stuck at 210. I checked wiring and even replaced sending unit at rear of the head. Pulled dash gauge out and found the solder path going to the temperature gauge burnt into. Put a jumper wire around burnt part and it works fine now. Gauge will peg while I'm trying to start engine after engine starts it goes normal.
 
Cox89xj ,good idea I will try that,also if that does not work my last draw is the chrysler sender. 58.00 vs aftermarket 8.00 in price so its saved for last.Im already into that new motor for a chunk of change.Ill post results if any..
 
UMMM....

So what happened?

My temp guage starts at 150....it pegs at start and drops back to 150, as the car warms up, it moves to about 230-235 and stays there. Gonna try checkin the back of the cluster, but I don't have an ampmeter....any other way to check resistence?
 
josh89xj said:
On my 89 xj I have a ongoing issue, I recently replaced the motor with a 87 xj 4.0. everything works great! Except the temp guage, I thermoed the engine and the coolant temp was 195 at running temp. But my guage reads 230 deg. I replaced the guage inside 2 times both are good but same problem,then replaced the sender on the cylinder head with 3 senders all did the same thing even tried a different sender and that just didnt work. Checked the grounds all ok what the hell else can it be???
Click to expand...

Where did you check the temp. from? The gauge measures the coolant temp. in the cylinder head and that's usually higher than the temp. in the upper radiator hose or the radiator. If the temp. difference is substantial, the problem could be a thermostat that's stuck almost closed.
 
Its the sender on the cyl head.Like i said before it worked until I swaped motors,same vin same cast#'s no difference in motors except the mileage.I tested it at the block,and the head and the recycling coolant thru the coolant tank all read 195 to 205 consistantly.But the tarded guage still reads 230,im tring to sell this xj so I can get to work on getting the commander that I so deserve.I also replaced all wireing to sender and guage ,it has to be the sender itself just not set correctly at the manufacturer.I bought 3 other senders from NAPA all do the same thing,anyone have access to a boneyard that can score me a OE temp sender w/guage?The dealer wants 55.00 for it and i dont want to pick it up then find thats not the issue and find I wasted another 50 on this same problem.Any help will do..
 
I might have to agree that it may be the NAPA part. The top of my sender broke off a week back or so and I replaced it with a NAPA part and all of a sudden I get the same exact simptom. Gage reads arownd 230 most of the time. Read 210 befor the old one broke. I may go get one from the dealer today and will let you know what happens.
 
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