Hi guys. I just replaced the thermostat housing on my 99 XJ8. The factory plastic one was no longer good, it was warped and the screws would just spin trying to take out the thermostat. Long story short, I replaced with an aluminum one, ordered a new thermostat (they sent the wrong one), so I put the car back together without a thermostat for the time being. I refilled all my coolant, charged up the battery (the car has been sitting a few weeks since I didn't have time until now), and now it won't start. I can't imagine why it won't start. Could it be that the car has a sensor that tells it there is no thermostat in it? Any suggestions would be much appreciated.

BTW, the car did start, run, and drive prior to me replacing the housing but I was loosing coolant from the housing, which was warped right aroung where the thermostat goes.

Thanks.

 

Can't see how changing the t-stat housing would cause a no start.... Check fuel rail pressure, my cat had intermittent no start issues due to a dying fuel pump.

 

Yeah I'm stumped, there are a couple electrical connections around the housing that I had to disconnect to do the swap, but pretty sure everythings back where it belongs. Is it possible disconnecting caused a problem? Also, I know its a long shot, but I was wondering if not having a thermostat in it would prevent it from starting (like a sensor I don't know about). Figured, everything else is electirc so theres a slim chance like those wires around the housing. If I think of anything else I'll report back, but all i really did was change the damn housing.

BTW you and I discussed the fuel pump earlier this year, I believe we changed ours around the same time. Thanks.

 

I changed my t stat a year ago. The car does not know if the t stat is there, so that's not your problem. I'd double check any connections you may have disturbed.
when you say it doesn't start, what does it do? Crank, or not?
Does it try to fire at all?

 

Do you mean won't crank or won't start?

 

Much more likely due to battery - there's nothing that tells the system you have no thermostat. Check voltage - just charging will not tell you that the battery is truly operable and the Jag electronics are somewhat sensitive to marginally low battery voltage.

 

Good question! Could be a cylinder washing issue, please indicate which one.

 

Ok guys, I took a video this morning, hopefully answers some questions. After shooting the video I charged my battery again, still have the same situation. Heres the video: ‪jag no start.wmv‬‏ - YouTube

 

First off the 2 plugs on the new thermostat tower are for the left and right knock sensors. The plug going to the coolant pipe with the broken clip is for the temperature probe none of which will cause the car not to start. Listening to your motor turn over it sounds like you have no compression typical of cylinder washing. Prior to your work on the engine did you run the car for a short period of time?

 

This might help No Start Situation 1997 2000 xk8

 

Gus, thats very possible, great point. The last move for the car was from my neighbors driveway to mine, about 20 feet, and left it there until I ordered/ recieved/ installed the part. So it sat for probably 3-4 weeks, but I know I didn't allow the engine to warm up on the last start (knowing that I was loosing coolant & not wanting to overheat the engine). I'll breathe a sigh of relief tonight hoping that you are right. I will let you know in the AM when I fiddle around with it some more.

 

Read Page 2 at the end post #29 from “Tempest” https://www.jaguarforums.com/forum/j...er-wash-49001/ I hope this helps.

 

Hi
The weblink in Gus's post #12 has a problem (https://www.jaguarforums.com/forum/j...ash-49001/page) full weblink is http: //www.jaguarforums.com/forum/jaguar-xj8-jaguar-xjr-27/yet-another-cylinder-wash-49001/page. I added the 2 spaces between http and //www to make sure you could see the full address.

Should be: https://www.jaguarforums.com/forum/j...er-wash-49001/
http: //www.jaguarforums.com/forum/jaguar-xj8-jaguar-xjr-27/yet-another-cylinder-wash-49001/

I was trying to open it just a few minutes ago and noticed the problem. Looks like the "page" is the problem.

Jim Lombardi

 

Thanks Jim.

 

Real quick, I decided to go outside and mess with it anyway. Gus, you are a good man. Cylinder wash it was. Took me about 20-30 minutes to get it started and had to run some jumper cables from my truck to the car while trying cause I could see it trying but the battery was draining too much. Longer story short, got it running, took it for a nice long drive, got home, shut it off, and drove it some more. The only warning still on the screen is the "restricted performance", I topped off the rest of the coolant, there is still some hesitatione around 30 MPH, I think maybe still needs to build compression to solve it? Thats my best guess right now, but I am thrilled that its running again.

 

Ok, here comes the new list.... So the cylinder wash worked, but like I said earlier; there was (still is) a big jolting around 30 MPH that levels off to normal operating once passed through 30 MPH. So I can eases thru it with little to no jolting, but if I actually try to drive normally, no dice. So theres issue #1. I took the car for about a 30 minute drive to pick up my sons glasses. Got out of the store, started the car, low coolant light now on. I pop the hood, fill the coolant and drive to AutoZone to figure out why the restricted performance message was there.

The news at AutoZone is that I need a new "knock sensor", I don't know what it is and they didn't have one. So I thank the man, buy some coolant and load the kids back up. Now we're at problem #3, dead battery. Thank God it decided to officially die and stay dead in the AutoZone parking lot, and beleive it or not, they actually had the right battery to sell me. So $160 later (not counting the coolant), I'm on the road again. Get to my dads and see that the coolant is being lost from a coolant reservoir that I didn't even know existed. It's right above the bumper on the driver-side. I don't know exactly where from yet, but its dripping off the giant nipple-looking reservoir.

So with the new battery, I'm presently down to [I think] three problems: 1) the 30 MPH jolting and 2) the knock sensor and 3)the coolant leak. Trying to figure out whats causing the jolting, my dad brings another good question to the plate; where the heck is the tranny fluid? Theres no dipstick? I don't remember ever looking.

And what exactly is a knock sensor? Would that possibly (hopefully) be causing this new 30 mph problem?

 

The knock sensors detect engine knock( google that) and correct. There are archives discussing reasonably priced sensor availability. And yes, the knock sensor COULD dause your symptom.

 

The knock sensor will cause a restricted performance this will prevent your engine from exceeding 2500 to 3000rpm. This could be what is taking place when you are trying to accelerate harder. Do you know if the knock sensor is on “A” or “B” bank? I do not know if you have a knock situation on your car but on mine I had to replace both knock sensors (one just the other day ) because they were malfunctioning (false reading). Did you clear the code and did it come back?

 

I'm not sure which knock sensor it is, the guy gave me a print out with the codes, they're in my truck, will look them up tomorrow. I don't think he cleared the codes, it still says restricted performance, but I did have to replace the battery and the codes were still there after installing the new one. I hope a new knock sensor will fix the present situation, but now I have to track one down. I also came across this video that I found helpful, maybe someone else will too:

‪Knock Sensor Operation‬‏ - YouTube

 

Hi
Here is a PDF file that shows Engine Controls sensors locations (including the knock sensors):

Crankshaft position sensor diagram.pdf

Here another thread with DIY information on replacing knock sensors:

https://www.jaguarforums.com/forum/j...ine-faq-45963/ If you have a problem with the weblink, then use this website address:
(www .jaguarforums.com/forum/jaguar-xj8-jaguar-xjr-27/how-change-knock-sensor-jaguar-aj27-engine-faq-45963/) Remove the space between "www and .jaguarforums" in the address.

Look at posting #1 and #2 for the DIY instructions and how to photos.

Jim Lombardi