Car: 1998 Jaguar XJR 114k miles

Seems I've put more money into this car than what I paid for it by now, but dammit I love the car. My next project with it is replacing the head gaskets. The head on my driver side seems to be burning quite a bit of coolant noticeable by the enormous amounts of white smoke coming out the exhaust on that side, a rough idle on start (most likely due to coolant clogging my up my plugs from seeping into the cylinders while it's sitting), a very noticeable drop in coolant levels and the most recent thing being my car kicking into restricted performance mode and the CEL coming on, probably a misfire code but I have not scanned it.

On a good note there is no sign of oil in my coolant or vice versa so I doubt that there is the possibility of any damage to the motor internals. The motor has yet to overheat so I doubt there will be any warping on the heads or block but I will have them inspected just in case. The coolant systems shows signs of over pressurization visible by small amounts of coolant forcing its way out by the hose ends.

The only reason I am attempting this is because I have done my timing chains and tensioners and have had my block stripped down to just the heads but I wish to god that I would have just done my head gaskets then because the idea had actually crossed my mind.

While the heads are pulled off I am getting them magfluxed, a valve job and full porting and polishing. I will be doing the porting and polishing myself with my friends help who has had experience doing this before.

As for my supercharger it's crossed my mind to rebuild the nose assembly but that is still up in the air for me, any recommendations for rebuilding the nose? I will be replacing the duct seals since it seems I must remove those parts of the supercharger to remove the heads. I will also be putting a 2.5 lb pulley on while I'm at it.

Anyways I won't be tackling this job until next Monday so in the mean time I'm doing research on the job and ordering the parts. I've been reading posts from people that have done the job before and feel pretty confident in my abilities to complete the job. If anyone has any tips for me for any of these repairs/modifications that you may have done yourself feel free to share them because I would very much appreciate it.

Will update as I work my way through the process. Maybe I'll take pictures and write up a little how to on how to replace your head gaskets as I haven't seen a write up on the forums for it yet.

 

Mine had a blown gasket, and it didn't show water in the oil until I pulled the pan. If you keep driving it, it's like juggling hand grenades, one day................bang.

 

Be aware that:

- the MLS head gasket from the 4.2L fits and is the preferred option on a AJ27. don't know if it fits the AJ26.

- the duct seals and flanges come in two variants, and only the later variant is available. those are the ones with the grooves. they cannot be mixed and matched. if you have the wrong flanges, you will need to buy both seals and flanges.

 

They fit AJ26 without any problems.

 

I'll have to see what came in my Eurospare head gasket set, not sure what kind they threw in there. I haven't been driving the car since the white smoke became a big issue, now it just sits in my driveway awaiting parts.

 

Eurospares looks to be composite gaskets, like orginal 4.0 ones. Best choice is to buy 4.2 MLS gaskets separately.

 

Hi. I have the same problem with the 1999 XJ8. Just keep pouring money into it, but love the car. 13 months after replacing the radiator, the radiator started leaking again. Had it replaced and continued to get low coolant warning. My mechanic gave me the bad news that he thinks it a head gasket failure. Said he proved it with a hydrocarbon test. I guess exhaust gasses leak into the coolant system and increase the pressure leaking to radiator leak. Does this make sense?

 

From my research a leaking/blown head gasket can lead to over pressurization of the coolant system. As far as it ruining the radiator I suppose that is a possibility but I have not dealt with that issue myself.

 

A little update since it has been a while:

Received my gasket set for the motor so now I'm waiting on the tools which should be here soon. I decided to spend some money and just purchase a master timing set kit that includes a crankshaft pulley puller/remover, vvt tool, flywheel bolt, two camshaft holders, pretty much everything you need and it's only $339 from KTC Auto which is a very good deal considering it's difficult to find a place that rents every tool. I rented the tools the first time and I was missing some and only had one tool to hold the camshaft, kind of wish I would have just bought the tools the first time when I was doing my timing chains and tensioners.

I've been getting distracted because I'm also building a v8 S-10 truck and I'm building pretty much everything on that truck. 2 projects takes a lot of time.

Here's a link for the tool set I bought in case anyone else is interested in them:
http://www.ebay.com/itm/251524351670...S:1123&vxp=mtr

 

Well months later a little update to the process... I spent a lot more time and money than I had expected rebuilding my chevy s10 v8 swap but now that that is finally done I can make some progress on the Jag.

Got the motor torn down and brought the heads to the shop to get them inspected/decked/pressure tested to make sure they were good to go. The checked out perfect no dropped valve seats/bent valves no warpage and passed the pressure test. Shop cleaned them up for me and put some break in lube on the valve caps (i really have no idea what else to call those things). Halfway through putting the car back together but I've been busy with school and work and life in general.

I'm not going to port the heads but I am going to port the elbow below the throttle body that attaches to the supercharger and possibly the throttle body itself and the part of the intake manifold that the fuel rail sits on because I had seen some manufacturing defects in those when I cleaned them. Oh and possibly the charge coolers once I get around to inspecting them.

I also just got in my spec transmission fluid and transmission dipstick from Eurotoys as my transmission pan gasket started leaking so I needed to replace the fluid why not do the pan gasket filter and do it the right way to make sure I filled it up to the right level.

In the future once this motor is put back together I'm going to do a leakdown test on it to see if it's worth doing anymore performance mods to.

If anyone has any questions on the whole head gasket replacement process I'm now an open book on the subject.

 

Before you put the heads back on, make sure that those buckets did not get mixed up. The top portion is a shim and they are a major PIA to set up if you have to. Most shops will grind the tip of the valve to set up valve clearance instead of changing those shims. When I do heads, I install the cams back into the heads, torque them down and then give the complete assembly to the machine shop.


If you decide to replace the shims, each size is sold in a bag of 10 from Jaguar. Many sizes and it can be very expensive, not to mention very time consuming.


Mike

 

Late update in the process, I've had the head gaskets done for a few months now, I think I finished in October. Put about two thousand miles on it no problem now there's other problems..... Successful head gasket replacement but now I have to figure out an ignition problem.