O.K......I gave up on the veggie oil conversion for the Mercedes and sold it. Gave up on the Jeep Cherokee diesel, and figured I'd just go for all out best mileage. Bought a 98 VW Jetta TDI. 1.9L Turbo diesel 5 spd. that supposedly gets around 45-50 mpg!? SO........a couple of questions. This guy has run Mobil 1 in it since 80k or so and just had the timing belt, water pump, and belt tensioners replaced. Anything else I should look at doing in the near future? I know nothing about them, but it looks like I'm getting ready for an education!

 

We had a 2000 TDI which we gave to our son. Averaged 40-42 all around mileage. Only problem we had was with glow plugs and the glow plug harness.

 

I could handle that! No injector pump problems or anything? I assume they have a lift pump also?

 

this has nothing to do with the engine, but watch out for body repairs, and replacement parts. the average cost of a 5mph crash with a jetta was almost 5 grand a couple years back...but I see you are looking at a 98, so I think you might be safe from the crazy costs.

 

VW dealers were always bad in the repair section - prolly a reason why they don't sell more units.

 

I'm in the same boat. I bought a used '04 [New] Beetle with 5 speed stick. Very fun to drive. Spirited city driving causes my mileage to go down to 36 mpg. Your older Jetta will get better mileage.

Sign up and read TDIClub forum. Do a ventectomy (if the older Jettas have them). It allows you to fill the tank up completely. Do a mufflerectomy. There are videos on Youtube that let you hear how it sounds.

Check your coolant reservoir for "coolant migration". Unplug the coolant sensor and check for coolant leakage. It will actually wick up inside the insulation of the wiring harness and take out the dash electronics. There is an easy mod to stop this from happening, if it hasn't already started.

Don't use any dealers. They're worse than Dodge when it comes to working on diesels.

Don't "check" the air filter. If you open it, replace it. The old filter will not reseal properly and will leak. It's essentially Schrödinger's air filter, while it's still in the box it could be good or bad. Open the box and it's bad. Use the cold region filter when you do replace the air filter. It makes a better seal.

Have someone nearby with a VAG-COM check your basic ECU settings. You can find them on TDIClub. Or you can buy the VAG COM cable online. The software is free, but won't work without a cable.

Have fun driving your TDI.

 

If it wasn't done with the timing belt change you should clean the intake manifold. It will be getting plugged. If Mobil 1 is synthetic it will be plugging the intake even quicker.

 

I am assuming the egr port on the intake? Or what is actually plugging?

 

Ah yes, the intake will have sludge in it from the EGR. It cuts down on the airflow and needs to be cleaned.

 

Oh, and get a spare relay 109. Actually, they're cheap. Get two from TDIparts.com and replace the one in the fuse box right away (if it hasn't been done yet). This relay will get hot and burn out. It supplies power to the ECU, so the car dies. The new version is a better design.

 

Been reading about that trouble! Thanks for the heads up!

 

03 TDI Jetta just turned 140k timing belt, two alternators, one starter. The rest just maintenance. Going to need to buy the second set of tires soon the breaks are great. 48 mpg. I drive 80 mph to work non stop and drive 10 mph home stop and go.

 

I love this forum. One post and you get it all. I've been reading tdi forums for weeks and haven't learned as much as I learned in this post. I'm looking for one for the wife. You all are great, thanks.

 

The new ones coming out are claiming mid 50's for mileage. We're looking at one for the wife.

 

Filled mine today for the first time........48.6 mpg! That's with quite a bit of "spirited" driving! I can't wait to see what it does if I baby it!