2004 Discovery with 90k miles. Replaced wires with Magnacor around 75k and new Bosch platinum plugs, performed all other services. I always use premium gas. Has generally run good, almost always keep it local on short trips but recently drove a few hundred freeway miles. After stopping a few misfire codes appeared and the engine ran rough. I also noticed mpg dropped to about 8 mpg from 10 mpg. Then a week later the codes disappeared along with rough idle. Now the codes are back but idle seems OK. Mpg still bad.

Possibly vacuum leaks or maybe front O2 sensors? The front sensors have oil around them and none have ever been replaced. Also I have some kind of coolant leak. Nothing visible and no condensation on oil cap or milky oil, but the resivior is constantly low and refilling doesn't help. Might have internal leaking in a few of the cylinders?

A local independent Land Rover guy with all the dealer diagnostic machines will evaluate the truck for $100.
Should I go with him, or try my own process of elimination starting with the front Bosch O2 sensors, available for $50 each on Amazon?

 

I wouldn't drive it until you figure out where that coolant is going. That's the #1 thing you can do wrong on a 4.6L D2.


The coolant could very well be leaking into combustion chamber causing your misfires and rough idle.


Did you check the engine codes while they were present? what specific codes they were that is?

 

So, what codes are you getting?

 

went ahead and had it diagnosed by a fairly well respected indy LR mechanic in Hermosa Beach CA named Dr. Vasken at Dr. Auto Tech. The latest codes were not misfire codes but right bank O2 sensor codes. After spending some time with it, he assumed the following:

- gas smell, running rich along with the bad O2 sensors explain the poor MPG. Guessing culprit to be bad valve seals (he did not take apart the engine so all guestimates). Also explains rough idle at times. about 2k to rebuild top end

- Low coolant could be piston sleeves giving out since no other visible signs, common problem according to Vasken. Not even worth attempting, he recommended buying an Atlantic British rebuilt engine with better sleeves- 6k+ with labor. Now I also had a faulty expansion tank cap, so I'm to monitor fluid level and hoping thats all it was.

Vasken has a cheap fix that had worked for one of his clients. For $700 he'll run some kind of stop leak through the block over successive runs, isolated from the radiator. No guarentees.

HAs anyone on this forum ever heard of that??

All replies greatly appreciated. I want to keep her but I cant afford to start spending thousands, would rather grab an LR3 which I'm told are much more dependable??

 

Get a few more opinions.

$700 stop leak should be the first clue.

In my limited >100k experience driving a D2 you do not go to the dealer after the warantee is up and you do not go to "foreign cars" mechanics.

LR only specialist shops... ONLY... Long story but noob LR owners are easy boat payments for many "foreign car" shops.

Clearly you should replace the O2 sensor before thinking about a new engine.

However, As Dane said, this could all be HG related... you are probably due for new head gaskets which should be around $2400 at a reputable indy LR shop.

Make sure you DO NOT OVERHEAT it and...

RUN FORREST RUN!

 

$700 for stop leak? That sounds very shady. Get your truck out of there fast before he does anything to it.

If you just have O2 sensor codes then why not just change the sensor?

I've never heard of a good mechanic wanting to tear into and rebuild an engine because of an O2 code. There has to be more to it than that. It really would help us help you, if you would get the exact code(s) numbers. Any autozone can scan the codes for you for free. If it is just a dead sensor then you should be able to replace it yourself. You really have to learn to do most of the repairs yourself on this truck or be prepared to open your wallet, turn it upside down, and shake every last dollar out.

 

that stop leak bs can be done at home for a few bucks. $700 for that is bs, is......well bs.

 

run, do not walk; away from Dr. Vasken.
replace you o2 sensors & never use stop leak

 

Thanks guys. What about the strong gas odor? Does that not indicate bad injector seals? If so is there an easy way to make sure that's the problem and what should new seals cost? What of the fact that only the right side bank sensors are bad an the left are fine? If just O2 sensors isn't it more likely that the fronts would go bad first?

 

Have you got any code #'s for us yet? Misfires left unattended on one side could damage the cat and O2 sensors for that side only. We really need the specific codes to do anything but guess at your problem. A lean or rich code might point to one cause, or a dead sensor code could be as simple as replacing it.

Bad injector orings could cause a gas smell, misfires, vacuum leaks and rough idle so yes it very well may be your problem. You will need to remove the upper intake to replace the injector orings. You could do a fuel pressure test and if you lose pressure after turning off the engine then you know you have a leak.

Here is a link for the injector o-rings>>> Fuel Injector O-Ring 2 Per Injector (BOSCH Injection) (Genuine Part # ERR7309 ) - Land Rover gaskets and seals from Atlantic British