so I am brand new and just picked up this 99XJR 105k about a week ago, I've been doing a ton of searching and getting all sorts of good info - thermostat, aux pump, clogged core ect. Maybe too much info for a new owner, so I was just looking for a little direct advice.

being unfamiliar with the vehicle im not sure if it has a normal operating temp range or if after warming up should remain centered on the gage. When freeway cruising 65-70 the temp gage runs a bit cold a bit over 1/4 reading on the gage and when idel or slow town cruising it runs in the middle right where I would expect it to.
. Now because of this I thought stuck open or no thermostat but the heat being great if idling over 3k or leaving it in a lower gear while driving to obtain such an rpm has me more thinking the clogged heater core or aux pump.

What are your guys thoughts and suggestions on where to start. Thank you

 

Looks to be in the right range. Not clear what your problem is? Not getting heat? Worried the engine is overheating? Also useful would be to know where you live, Cold starts in winter a whole lot different than Riyadh . . .

 

Sorry for the lack of information - both those pictures are after the vehicle has completely warmed and come to temperate but if cruising the freeway the temp actually drops - 74 degrees out today when operating.

I get no heat from the vehicle at all no matter the temp unless the engine is at about 3k or greater for 20-30 seconds after warm. then the heat starts to come in and feels strong. no matter the setting on the heater there is no heat only cold air if the engine is under about 3k rpm even if at normal operating temp.

 

Having a scan tool that displays live data should be your next move. There’s plenty of threads to search to get what fits your budget and gets the job done. You’ll need it at some point anyways.

If the coolant is topped up and you’re driving on the freeway, I am assuming that you may have a thermostat issue or the heater core is still clogged. There have been some times where I’ve had to flush the heater core with white vinegar on customers cars multiple times before it was free flowing. I’d highly recommend having some really long hoses with clamps on them and/or 90* bent hoses so you don’t get a ton of water on top of your engine.

1 last thing, you absolutely need to know if both secondary timing chain tensioners have been replaced with the aluminum ones. Pull *both* valve covers if you don’t have any record.

 

Yeah to my convince I found the scan tool I have doesn't communicate with the XJ so I'm on the search for a unit that will.

 

Do the x308s have the coolant pump for the heater core like the x350s do?

 

I am far from even a novice on this platform but there did appear to be a little electric pump under the coolant resivior.

 

Yes auxiliary water pump on drivers side (us) frame rail

 

The first thing to check is whether the aux electric pump is running. This pump is there exactly for the purpose of providing good coolant flow through the heater at lower engine rpms when the output of the main coolant pump is lower and insufficient to provide good flow of the coolant through the heater core. Good heating at ~3000 rpm and above suggests that the heater core and the control valve are probably good.

Keep in mind that that the motor of the electric pump is not connected to the pump impeller via a shaft but by a magnetic "coupling". So, you may have a case that the electric motor is running but the pump impeller is not turning. I think there are some good posts in this forum (or somewhere on the net, cannot remember) about inspection and freeing of seized pump impeller.

 

Thank you, I'll start by pulling the pump and see what is doing

 

Welp, pulled the pump and the control valve all seemed well but after a clean heater core back flush still no heat at idel but a small improvement as heat seems to build at about 2k rpm now. Only thing I can guess is that it needs a new aux pump?

 

Did you verify that the pump impeller is not seized? Did you open-up the impeller housing as shown on this pic:

I found the article I mentioned earlier, PDF file attached.

 

Your coolant reservoir bleed lines appear to be reversed. They should cross, as seen here:

(AFAIK)

 

Good catch thank you, I'll confirm and switch 👍🏻


Opened the housing and took apart the bottom and it spun freely and I can't believe it.... I didn't even check the top end - I had originally thought the control valve was the pump and after taking it out and taking it apart and realizing this ain't no pump I was a bit flustered. That being said I did learn and made for an easy core flush so still a win.

I'll reset the coolant lines properly and rip the pump out again

 

Re routed the coolant reservoir lines as pictured (thank you)

and driving today, significantly cooler here today and could never get the car near operating temp when cruising so unless instructed otherwise Im going to replace the thermostat and re investigate the aux pump.as heating still doesn't really exist except for when pulling hard through some gears (at which point the cabin becomes incredibly warm!)

Thank you guys for the help