2004 XJ8 was leaking fluid at or possibly right above the auxiliary coolant pump. I replaced the pump and the hose, but pinched the line running to the thermostat. It over heated after 20-30 minutes. I let it cool and tried bleeding the lines, drove it 10 minutes home no problem.

Next day overheated after 20-30 minutes and over heated again. It wouldn't start after it cooled, so i towed to my garage. I discovered the pinch line and replaced it.
Now it will sometimes rough start and go into limp mode or not start unless I pump the gas then restricted performance.
No visible mixing in the coolant and performed a block test 3 times and it passes. Liquid in vacuum tube test.
Codes: p0300, p0301, p0302, p0304, p0308 - misfire on 1, 2, 4, 8
Codes: p1313, p1314, p1000(I reset codes initially)







I'm thinking spark plugs and check wires next?
Any reccomendations?

 

Just shooting from the hip here, overheating could have damaged plugs or coils.
So if the errors are reliably reporting 1, 2, 4 and 8, try shifting a couple of coil packs from (3 and 5 for example) into position 1 and 2 to see if the fault shifts position.
That way hopefully you can quickly tell if your looking at plugs or coils.

I would also just check the integrity of your Ground earth point (G26 or G30) behind LHS or RHS shock tower for any issue as the coil packs are grounded there. You might have inadvertently disturbed that earth with your recent work and earths are a issue with our cars.
Left (G30) or right (G26) depends on left or right hand drive.

 

I hope to get some work in today. I will clean up or replace those grounds too. Thank you for the suggestion.

 

valve seats are done

 

Another suggestion, check your auto trans fluid to see if burnt. If so, consider flushing it. Since the auto trans cooler is in the radiator, substantial overheating can cook the trans fluid which loses its lubricating properties fairly quickly, spelling disaster for the transmission. I finally learned this the hard way, after having to rebuild transmissions on two vehicles following overheating events (first one was on early XJ6, second on F150).

 

Thank you for the transmission fluid tip.

I changed all of plugs, they were oil free. I changed the oil and it looked normal.

The battery was dead, and I know a low battery can do some weird things. I jumped it and it showed 2, 4, 6, 8 misfire... I had a loose wire at 2.

Excitedly, I started it again and it went into limp mode with a misfire on all cylinders. I believe the exhaust is more white than normal, but the coolant level is holding strong.

Update: i just saw the valve seats post.

 

It's starting to sound like a blown head gasket in bank 2, as coolant exiting the exhaust will cause white smoke. You should be able to loan a kit from Autozone or O'Riley's to pressure test the cooling system.

 

I originally did that test and it passed, but I agree. I'm not making it better with every test start. Head gasket, valve stems, maybe more. I need to make room in my garage for this project.

 

Sorry, I missed that in the original report.Sometimes that mystery coolant leak ends up being the head gasket. This may sound crude, but if this ends up being the case you could try some of that head-gasket-repair-in-a-can stuff. Contrary to popular opinion, they will not clog your system and cause overheating, and can be a permanent repair.

 

Blue devil?

 

Also, it doesn't seem to be leaking coolant or very little. But it's still worth a shot

 

Losing coolant is the issue, not leaking it. If you are seeing white smoke, it is likely steam exiting the exhaust. Another clue is spark plugs that are exceptionally clean (i.e.steam cleaned). Yes Blue Devil is good but way overpriced for what it is, I have had good success with Bar's Leak brand as well.

 

Best-rated is Steel Seal. A clear, filler-free, plastic that heat-polymerizes to a hard solid in-place. Wants to be applied in water-only, anti-freeze flushed out FIRST. Read the FINE print, IOW.

Next best, K-seal - operates with copper & ceramic particles, siltation-style, so doesn't care if the coolant is glycol or water.

Filling out the backfield: Blue Devil, Barrs leaks - both Copper & Aluminium?
Caught early enough, any of these MAY buy you some time, but only just.

Says he already involved in head gasket repairs to the 5.0 AJ133 in the Range Rover... after trying all or most of the above...

Nature of the beast. Not limited to JLR motors. Aluminium just MOVES a helluva lot more than cast iron when it gets hot.

Harry Miller had a fix for that. Integral cylinder heads == no head gasket == nothing to fail!!

Valve jobs were a right b***h kitty, though.

TANSTAAFL.

 

I did a head gasket leak test on my 2006 SV8 after several coolant leaks and overheating issues, and the color change in the BT700 block tester kit (bought from blocktest on ebay for $42.99) indicated combustion gas in the coolant. My top radiator hose had backed off several times, even with two clamps on it, indicating excess pressure in the cooling system. The system would hold pressure over night when pumped up to 20 PSI, but I was loosing coolant when driving. I considered the common head gasket sealers and ended up trying the K-Seal head gasket sealer because it did not require thermostat removal. The result was inclusive because my radiator developed a bad leak at the top of the right end tank and I needed to replace it and was in the middle of the process when I had to move the Jag for a house remodel project and the General Contractor sent it to his brother's shop where the radiator did get replaced but the air suspension is leaking at the front so no extensive driving yet. The brother said he did let it idle for an hour and saw no leaks and it did not overheat, but I don't see how the K-Seal could fix a head gasket leak if it did not prevent the radiator leak. I'd suggest you do a block leak test to be sure of your situation, but don't buy one from AutoZone because they sell a Chinese knock off of the BT700 and the one I bought first broke immediately. Also as an aside, do not buy a radiator from Rockauto as the one they sold me and still list as fitting my 2006 SV8 has no transmission cooler and is not even close to the right one, and they will not accept a return nor refund the cost.

 

Thanks for that. My guages were built when America still made stuff HERE.

I'm actually chasing a used motor .. as fallback, given it will need a complete rebuild - before I pull my one.

I also have some "Thermoseal" already inbound. Has been known to work on one of the worst light-alloy motors ever mass-produced. Cattlejack "Northstar" as couldn't even retain its own head-bolts!



As to THEIR call for a thermostat pull?

... "should be OK" to simply suck the juice into the block side of the 'stat rather than the rad side of the circuit.

Goal is it is circulating from cold - warms up as the block warms up. AND NOT.. waiting in the rad & header tank to enter the play until the coolant in the block is already hot.

More when I know more.....

PS: You MAY need a new rad cap. They do not last forever. Only had that pressure build-up when one got clogged. Otherwise, the built-in relief vents overheated gas and coolant, which appears down the engine bay side of the header tank, heading for Mother Earth and trickling off all the stuff in between just to add to the confusion. Usta be, a filer neck had an overflow hose to mange that.

 

Yes, I did replace the cap and yes, I have had coolant blow back on the engine from under the cap. By excess pressure I meant pressure at the rating of the cap which I seem to remember is 20 psi for the supercharged V8 vs the usual 16 psi.

 

I hope that is correct, even if I think it wrong to have done it in that manner.. as I have been talking myself OUT of the supercharger game!


Larger rad could make sense.

Over-stressing already-dodgy components? Not so much.
More than a few places, USA, ambient average is only 10 PSIG.

Went up to take an hour or three of dual out of the airstrip at Leadville, CO once. Pressure there is ony 2/3 of standard atmospheric. Chickened-out. All they had on the line were Cessna's. Even an ASEL-holder has to have some standards.

 

Looked it up and it appears the cap is 140 kpa (20.31psi) for all models, not just supercharged ones. Looking back in my notes, I replaced the 140 kpa that came on it with a new 140 kpa cap.

 

There is more than one available. Ambient altitude thing? I keep two or three spares to-hand for the two JLR motorcars.. because they clog too DAMNED easily. And ruin their gaskets too rapidly.

Whomever at Stant lost the bid for a well-proven rad cap might have simply disliked British "kit-cars" (fix faults all week, drive only on Sunday) enough to no-bid?