I have a 1997 land rover discovery sd.
I bought the car with 113,000 miles and a blown head gasket
i have since replaced both head gaskets including the head bolts and all other upper end gaskets and also had the heads shaved to be perfectly flat.
when i pulled the motor apart there was no theremostat, but i have replaced all the radiator lines and put in a new thermostat.
now for the problem.
sometimes when i start it the idle will immediately climb to 2500rpm until settling at 2000 rpm. then after severa; minutes of this, it overheats and blows water out the overflow cap.
other times ill start it and it will idle fine at about 700rpm until something happens and the idle gos way up and it starts to overheat.
im already way over my head and am just wondering if there is a valve or vacuum line etc, that may cause this problem.

 

Do you have the belt routed correctly?
http://www.roverparts.com/TechTips/s...g_defender.cfm

A vacuum leak will cause a high idle, does it idle high when warm or cold?

 

Yes i believe the belt is routed correctly, And as for the high idle, sometimes it will start and the idle will go to 2000rpm then come back down to about 700rpm, but most of the time, i will start it and the idle will go up to 2000-2500rpm and stay there, until i put it in drive and then it will go to about 1000rpm. dont know what it is.. This rover is posessed! it needs a mechanical exorcism! also it will climb in temp until something happends or something opens and it overheats.

 

I would say the high idle is probably your TPS or IACV. I don't have a TPS on mine right now and that is exactly what it does. Almost the exact same values too. Idles at 2000 rpm then dies off to 1000 when placed in gear. That's what I would check first. The TPS. Good luck.

 

ok so the throttle postion sensor, where is that exactly?
and also where is the idle air control valve?
im generally profeccient in motors, but not in foreign cars

 

They are both on the intake plenum. Right next to each other. It does sound like your TPS is going out. The IAC is a stepper motor, so you might try taking it out (not touching the plunger) and cleaning it with carb spray. Clean all of your throttle body while you are in there.

Just an FYI, if you move the plunger on the IAC, you will need a Rover scanner to have it reset, same thing if you move the TPS. Replacing either of these MAY require a reset, sometimes you get lucky.

PS, the Rave manual has everything you need to work on a Rover. Free download in my sig.

 

thanks! ill try both and see what happens.

 

tried taking both out and cleaning well, made sure to avoid plunger, doused the entire thing with carb cleaner, and nada. but its all good!, i had someone make a cash offer of 4500$ and frankly im takin it! i sign over the title tommrow, but maybe the poor soul whos buyin this thing will find you forum! thanks for all your help!

 

holy crap. well, good for you...