QuestionOur 2000 Discovery II with a V-8 misses when it is idling or under load. We had new plugs installed and it didn't change anything. The car has 51,500 on it, is one owner, has had all the checkups done by dealer to 50,000. It recently developed a miss. The check engine light has been off and on for a month or so.
Any idea what a fair price is for valve cover gaskets to be replaced? Thanks.
AnswerHi Lois,
I'll tackle the easy question first. Valve cover gaskets are about $120 to replace. You could buy the gaskets from the dealer ($25 each) and have a local mechanic do the work BUT there are some complicated components that have to be adjusted/moved in order to remove the covers and install the gaskets. I'm proud to do most of the work on my Disco BUT I 'bit the bullet' and had LR do my gaskets. Its worth the 1 hour labour charge to have it done right.
Second question: misfire or missing under load. Tough problem to solve. I am aware that engines in Disco II's are prone to have exhaust valve problems. Buildup of deposits on the exhaust side of the system cause the valves to not function correctly - sticking. As the build-up increases, the driver will notice sluggish engine, hesitations, misfires, and loss of power - especially after the engine has reached its average running temperature. Some owners notice this even more on very hot and humid days. Only a LR dealer can tell if you have this problem.
Don't bother with additives...on the exhaust side of the engine, everything burns up and no chemical could survive after the high-temp combustion process. The only solution is a "valve job": cleaning and/or replacement. Bad news: usually costs about $2000 US. Good news: better fuels exist that can reduce this from coming back to haunt you (Octane 94).
The next time you have a check engine light (CEL) do the following:
look under your passenger seat for a small OBDII error code display unit. About the size of a crayon box or a man's wallet. It should have a wire attached to it and you can usually extend the unit out from under the seat by 5-7 inches.
Turn the ignition key to the maximum position WITHOUT turning the engine over (sort of a notch before the engine actually starts). With the ignition on, take a look at the OBDII display and see if there is an error code number. My OBDII has a red plastic cover and the codes are in yellow (easy to see during the night). These codes are errors that have been trapped by the ECU (electronic control unit - engine control unit) and indicate problems with various sensors.
If you have a CEL code, its easy enough to find the failing component and thus reduce the troubleshooting time.
I like the Series II Disco's but these exhaust valve problems are a real disappointment. The earlier Disco I's have different engines and are not affected by this.
There are other causes of 'missing', misfires and power loss during operation such as the spark amplifier module (SAM) or the Throttle position sensor (TPS). These two problems are repairable to the cost of approx. $500.
The coil pack is another source that could cause a sensation of 'missing' with the engine. $600 from various aftermarket autoparts suppliers OR $900 from dealer. Then there is the labour - one hour max.
I hope this gives you some clues as to what to expect. I hope the problem is a simple one and wish you success in having it solved. The fact that you have it so well maintained will pay off in the long run.
Best of luck,
JohnMc
