QuestionJohn,
I have a 1995 land rover discovery 3.9 5spd that I have owned now for a week I have already driven it for about 500 miles i noticed a slight knocking noise at the low end of the engine at idle around 750rpms but as soon as you rev it the knocking goes a way with no power loss on highway and the check engine light is not on. today I took off and noticed a bucking in the vehicle but after it warmed it went away.
third the abs and the SRS light are on. I had them tested and was told the airbag has an open systema nd needs to be replaced is this true.
i apologize for all the questions just hoping you could help shed some light.
thanks
Joel
AnswerHi Joel,
you and I share the same vehicle. My 5spd '95 Disco is white and was named "Simba' (a LR tradition to name your vehicle).
The normal idle speed is 750rpms. If it goes lower than that you have to adjust the idle or look for possible causes.
The slight knocking could be a few things, quality of fuel, condition of engine, ignition tuning. Assuming you have a V8 petrol, make sure you purchase the best fuel you can, Octane of 91 or higher. Anything else could be a problem and you'll hear your engine complaining soon after. Tapping noises are a sign that fuel is the problem.
The exhaust valves can develop carbon deposits over time. Depending on how many miles your Disco has, it will eventually have this problem. On newer Disco's, this is an even more severe problem and usually after 50,000 miles a complete valve job is required. Our older 3.9l engine seems to keep on working thru this problem BUT it does get a bit noisey and maybe that's what you're hearing. If the noise increases you'll have to consider having your engine cylinders pressure tested...just to make sure.
Consider tuning up your Disco. Replace all the fluids: brake fluid, transmission, transfer gearbox, coolant, oil and replace your gas filter too. Do this every two years.
Change your air filter every year. Spark plugs and wires every two years, distributor cap and rotor every 4 years.
All of these things will go a long way to reduce engine noise and increase the longevity of your Disco engine, tranny and brake calipers.
The bucking you noticed may be the fuel, the fuel pump or the injector system. If a CHECK ENGINE light came on, here's what you do:
Turn the ignition to position I. Look under the passenger seat for the On-Board Diagnostic (OBD) display. A number should be present. Write the number down and look up the code. Advance auto parts are a good group and they can help with this. They've been known to read codes and reset them for free. Of course, if you need parts, they'll be willing to help you with that too.
The ABS light is common problem with LR's. It can be the wheel sensors failure, the ABS pump, modulator, relays, its complex and costly to repair. I've replaced the sensors and still the light comes on. You can either have LR repair the ABS system or learn to live with normal brakes. Think of the ABS light as a smiley face...sort of. Tell anyone who ask's : "its just a reminder that I have an ABS system". Its also a reminder that it sucks!
The SRS is more serious. I believe the manuals state that after 10 years the SRS bags have to be replaced. OUCH. I don't know if your Disco was in an accident or not ... so a visit to the LR dealer may help solve this problem. Some owners have been known to pull the fuse for the SRS and think the problem goes away. It does until its sold and the new owner has to fix it. You have to decide if you want to have a functioning airbag feature or to turn if off (pull fuse) and take your chances.
Lastly, there was a fuel tank recall recently. Land Rover HQ will replace the fuel tank and even the fuel pump on your Disco. Apparently, the fuel tank can develop cracks and could be a fire hazard. Again, visiting a local LR dealership and registering your name as the new owner will help you in many ways. You'll be able to find out what work has been done on your Disco, repair the SRS light, find out if your Disco's fuel tank was replaced under the recall.
By the way, Land Rover pays for ALL the work Don't let the dealership trick you into paying for anything associated with the fuel tank. If LR determines that your fuel pump is too old and rusty, they'll replace that too - free of charge. If fuel lines could be damaged due to the recall work, they'll be covered too.
Best of luck,
JohnMc
