Is anyone able to help me with this issue?

A month ago I had the bottom tensioners replaced at 152K miles on my 1999 XJ8L. Certified Jaguar mechanic in New Orleans. $3K. No more rattling noise.
Prior to that and only on a cold start, I continue to have white-blueish exhaust coming out of both sides of the exhaust pipes right after I start it. Then, it goes away. It only does it on a cold start.

After the replacement at about 100 miles later, I had a yellow light tell me the I was having restricted performance. It happened right after a fill up. I read I might need a new gas cap so I ordered one and the light no longer pops up. Revvvvvved it up to over 3000 RPM several times and no light or sluggish feeling. Runs like a champ except for the smoke which makes me think something is definitely off. Does anyone think this is all related? Is the white exhaust an indicator of some mysterious issue? Should I be putting in a better gas or additive?

Otherwise, the car runs perfectly after the recent replacements.
Please help me out and thank you in advance.

CW
66 year old lady needs help!

 

Are you losing coolant? Is it overheating? If neither, maybe just moisture in the exhaust system -- otherwise, head gaskets and the most common. Maybe have your mechanic run a compression check or other test for a blown head gasket.

 

Fine on coolant. Definitely not overheating but it is very humid here in New Orleans. A compression check is in order so thank you. I'll post the results.

 

Missed white-bluish smoke: compression check will also show worn rings and valve guides leaking oil after the engine shuts down.

Fairly normal on a 152K engine.

 

If the white smoke lingers it's oil. If it dissipates quickly, it's steam. A by product of Cat. converters is moisture in the form of steam on a cold start. Oil would leave residue on the bumper, steam would not.

 

I’m with Jhartz on this.

So my 98’ XJR has 254K miles on it with the original engine and I did replace the valve stem oil seals on mine (at 234K miles) when I replaced the head gaskets and set aside it had a blown head gasket, prior to that when the engine was running good it had blueish smoke on cold start ups as well. In my opinion unless you need to have the head gaskets replaced, it simply is not cost effective to have just the valve stem oil seals replaced.

I'm sure I’ll get chastised a bit for saying this but if you plan on keeping the car a long time and it’s in really good shape I say go ahead and have the head gaskets replaced because the cylinder heads will need to go to a machine shop to have a valve job and the heads milled and valves (very important) adjusted. It should run substantially better after a valve job.

If I had to guess what you’ll get charged for a complete head gasket job, I’m thinking $3K-$5K. I highly recommend taking it to a well known Independent Jaguar repair shop. I know that’s a lot of money but some of us really love our cars.

 

99 4.0 nikasil block. Best and cheapest is to run a quart of engine restore every oil change in place of 1 of the 8. Back then had many customers with blow by issues and either and ring job or spend $10 extra each oil change on engine restore. Have used it for decades on issues like this and works most every time. Avail at any auto parts store by that name

 

valve stem

 

I had the white smoke issue on my '99 supercharged (AJ26S, Nikasil) accompanied by immense oil consumption. I tried to fix it by cleaning the part load breather, replacing the passenger side valve cover because the oil separator was broke, put engine restore in - nothing helped. Finally, I replaced the full engine with a newly revised one which was a lot of work but now it's running great and it's a good feeling to have all the important seals new.

We disassembled the old engine, but we've couldn't find the cause. The bores were alright, but there was a small issue with the head gasket, however I'm not sure this explains it. And according to everyone I've talked to it's hardly never due to the stem seals.
Good luck...

 

The causes of blueish smoke are usually as follows:

1. Smoke for a fairly short period of time after cold engine start; no serious oil consumption - valve stem seals; oil runs down the valve stems overnight and is burned at engine start.
2. Smoke all the time, especially when revving the engine; high oil consumption - worn cylinders and/or piston rings.

The valve stem seals can be replaced in-situ but it is a slow and tedious job. With the camshafts removed, compressed air or a rope inside the cylinder are used to hold the valves in closed position while removing the valve springs and stem seals. In this case, a special valve spring removal tool is used.

However, if the smoke on start-up is for a relatively short period of time and the oil consumption is not serious, it is probably not worth the trouble replacing worn valve stem seals. They will do no harm to the engine (only to the environment).

 

Really? This one's on Facebook Marketplace:
supercharged v8 jaguar XJR with only 82,000 miles and counting Runs amazing and is very fast, tons of maintenance records Just passed smog Interior is perfect Exterior is perfect Registered until 2023 Clean title in hand Let it sit for a few weeks on vacation and I came back to smoking out the pipe, could be an easy fix, I don’t have time, will still drive fine

Fix it with a can of engine restorer?

 

Only thing Jaguar run through these engines is BG44K.

If sat in cold weather, smokey startup can take place as water in the exhaust gases off.

 

I never hear this mentioned so will offer it up as a possible cause. My wife's XJR developed the white puff of smoke on cold start only - turned out to be leaky injectors slowly bleeding down. The dealer ran some injector cleaner through the system (in situ) and the problem was fixed.

 

White smoke can be both: Either it is normal (condensation of water) or it could indicate a head gasket leak (in which case the white "water" smoke would be coolant...).

PS: It's the amount of white smoke: Just a bit of thin, ghostly white smoke is normal, probably only visible at colder temperatures. The other white smoke from coolant is pretty thick, depending on the degree of damage to the head gasket. In both cases that should be mainly visible at start up, until all the "water" is vaporized. Obviously, if there is a massive coolant leak at the head gasket, the smoke would probably not stop when driving. (It's kind of like the next step towards a new engine-development...: the HHO-engine - but only the early development stage, where they forgot to do the electrolysis first... )

Gray or blue smoke is burning oil. Causes could be: Failing PCV Valve, bad piston rings or - and I think that is what my V12 has (I have not started yet fixing it up): Leaky valve seats (a '90 V12 has 24 of them, which is less than a V8 with double-dual camshafts, as that would be 32...).

 

Because unless the guy is lying, I don't see how the thing could pass a California smog test recently, if it's burning that much oil?

 

A little white smoke on a cold start is really nothing to worry about. Just be sure to
check your coolant level at regular intervals.

 

I would seriously doubt that "a little white smoke at cold start-up" is why he's dropped the price to $3k.