Back Crossover/Heater Manifold Repair

[serge1060]

Thank you

 

[Mozambique]

On the V8 its eight individual gaskets, one per port

 

[Izanagi]

Hey all, long time follower first time poster. I just need to change the coolant temp sensor on that rear heater manifold. No leak or anything. How big of a job is that?

Many thanks,
David

 

[ugmw177]

depends on whether it is the SC v6 or the n/a v8. in either case though, if you are going to the labor to get access to that, you might as well change out the heat manifold as it will be brittle and eventually leak

 

[Izanagi]

Sorry for the lack of relevant info lol, but thanks for the reply! It's the AJ133 n/a V8. Just wondering if there's a way to get around the back of that rear crossover pipe and swap the sensor without having to take the whole intake off - or will be that be necessary regardless?

The reason I ask is because I recently changed the water pump and thermostat and the truck started throwing a P2185 code about a week later. I swapped out the coolant temp sensor near the thermostat, but the code is still Permanent (which is what leads me to think the sensor on the rear crossover pipe may have gone wonky).

How sensitive are the ECUs on these trucks to aftermarket sensors? I used the cheap WVE brand off RockAuto but could easily try replacing it with an OE LJR sensor if it might make a difference...

 

[jlglr4]

I think you should be able to reach that back coolant temp sensor without taking the intake off, but you might need to remove the windshield cowling if you aren't taking off the intake. I have an SCV6 and did the whole job with the intake off, but I was thinking at the time that removing the cowling might give enough space to get back there if needed. Not sure though.

I think what ugmw177 was getting at in the above post was that, if you are going through the effort to change that temp sensor, might just as well change the crossover as well, i.e., take the intake off and change both the pipe and sensor more easily rather than struggle to replace just the sensor. Do you know if the rear crossover has been replaced in the past? If it hasn't been replaced, I tend to agree that it should be done and might as well do it now.

As for sensitivity to non-JLR sensors, my understanding is that the ECU compares the rear temp sensor (hot, out of the block) with the front temp sensor (cool, out of the radiator) as part of it's routine to make sure everything looks correct. So, I can imagine a cheap sensor in one spot could screw things up. Still, if you had the error before you changed the front sensor, the back sensor will likely need to be changed and I'd do that first - or maybe both simultaneously just to avoid having to bleed it twice.

Since this showed up right after a water pump replacement, are you sure the coolant system was fully bled out? Just thinking that an air pocket might prevent coolant from getting to the sensor. I'm not entirely sure that would cause this code, but seems possible.

 

[Izanagi]

Thanks so much for the super helpful response - all totally valid points. I'll start by bleeding the coolant system again and go from there.

In agreement that I should change that rear crossover pipe if the intake is coming off.

Will report back with findings. Many thanks again!