My 99 XJR is blowing a lot of smoke at start up...no signs of oil leaking anywhere as of yet...any suggestions on what the prob may be?? Smoke is only when the car is started white like head gasket problems but no oil and compression seems fine.

 

What oil are you using and how many miles on the car?

 

96000ish castrol gtx high millage 10w30

 

White smoke is coolant and could be head gasket. Are you loosing coolant or oil in coolant or coolant in oil??

 

not as of yet but will keep an eye out for it...

 

GOODZ- white smoke can also be brake fluid being pulled out of the brake vacuum booster at start up. Very carefully monitor your master cylinder for small amounts of fluid loss. Lets hope thats it because the fix is a whole lot cheeper than the alternatives.

 

understand the concept tarheal cracker but how would brake fluid get in to the engine smoke is coming from exhaust/

 

Leaking rear master cylinder o-ring/seal allowing brake fluid into the vacuum power brake assist, from there to the intake manifold via vacuum hose and into the cylinders.

 

if this b the case will the brake booster be shot...my pedal is a little soft...stops fine but soft...fluid level is fine but also was recently serviced all fluids were topped off etc...

 

GoodZ - If the problem only recently presented itself the vacuum brake booster is probably okay. It takes a lot of abuse to hurt that rubber bladder inside that booster, altho it's not unheaed of.

I've had 5 high milage Jags over the years and only 1 brake booster failure . Now if the problem has been present for a long time-- well anythings possible. Seems to me that a quick test is to disconnect the vacuum from the booster 1st thing in the AM before you start. If no white smoke you got it isolated.