92 xj Low Running Temps and No Heat.

As the tittle says i have low running temps. Around 70-75 degrees on the gauge while driving. Then when parked and idle it jumps to just under 100 untill i start driving again.

The heat stays cold even at 100 and all my lines get hot.

I just installed a new t-stat (192) and flushed my heater core about a week ago (back and forward flush with minimal crud)

My blend door seems fine as i feel it open and close (still cable type, not electronic). Im thinking maybe i didnt flush the core well enough? or maybe i have to flush the rad.

Are you expressing your degrees in Celsius? If so what does 45-70* C = in F* degrees?

Your temp sensor at the back of the cylinder head on drivers side is probably faulty.

It has a push on connector with a white plastic top on the sensor itself.

my2monkeys said:

Your temp sensor at the back of the cylinder head on drivers side is probably faulty.

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X2 on this.

my2monkeys said:

Are you expressing your degrees in Celsius? If so what does 45-70* C = in F* degrees?

Your temp sensor at the back of the cylinder head on drivers side is probably faulty.

It has a push on connector with a white plastic top on the sensor itself.

Click to expand...

Sorry was actually 70-75 in C. Just past the first notch with no difference in the air temp. Its about 167F.

Ive also checked for an air lock by cranking the heat while running and filling the rad. I went for a drive after for about half hour with no change. Just checked the over flow and was down between full and add when it was on full before so not much difference.

is there a way i can check the sender unit? Its a single wire so it would have a current flowing to bring it up to 70 but is there a voltage its suppose to be at?

Use a factory stat part number 83501426.

cruiser54 said:

Use a factory stat part number 83501426.

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the one is just swapped out was a 95. ( just did an engine swap with a bored and polished one and took the t-stat from the old one. Swap that one out because i thought it was stuck open)

And i should be getting a little heat if it was a to small t-stat issue shouldn't i? Not the absolute no heat and really low temp issue im having.

Im searching for someone who has the sending unit atm to swap that out and see if it works.

My guesses,

Low temp ... t-stat stuck open, temp sender shot.

No hot air at the vents - Water pump not working, Heater core blocked

Have you checked the heater control valve (assuming you still have one after the engine swap).

Have you verified temps with an IR thermometer?

Pelican said:

Have you checked the heater control valve (assuming you still have one after the engine swap).

Have you verified temps with an IR thermometer?

Click to expand...

The HCV is brand new replaced during the swap because the old one broke.

the engine is WAY hotter then 70 i can tell you that just by feeling the hoses but i do not have a IR so i cannot confirm. Couldnt go down and pick up a sender unit today to confirm that is the problem but was able to flush the core again today with some solution and its still the same and looks pretty darn good tbh.

Im going to see if the sender unit makes a difference in the temps on the gauge and if its running hot then i know its probably the water pump. (I have a slight noise coming from somewhere on the belt intermittently but doesnt last long and havnt traced it to anything just yet.

pop the belt off and see if there is any play at all in the waterpump pulley. it should not move at all... if you can wobble it around by hand the waterpump is shot.