300tdi Disco - Slow as f#$k!

Hi all,

I've got a 1996 disco, 300tid, with 155,000 miles on the clock. It had the head replaced june last year (after i cooked it completely), and since then, it has been really slow.

It struggles to maintain speed up hills, or if it has a trailer on the back, it just screems untill your at about 3 or 4k revs to change gear.
It can sit at 80mph - but just takes about 4 hours to get up to that speed!

Any suggests would be appreciated!
I'm willing to try anything!

Thanks,

Josh

Usual Tdi performance enhancers on high milers are to clean out the intercooler and the replace the intercooler hoses as the original ones can collapse. Of course, it all depends on if you did any more damage when the head was knackered.

Matt

Changed the air filter lately?

Ever had the IP timing checked?

Mind you - at 4k rpm it will be screaming, 4k is the redline for a 300tdi - not the best way to drive a diesel turbo that

What happens if you change early - say 2.5k rpm, max torque is where your turbo is doing the most work for you, should be at about 1,800 to 1,900 rpm on one of those.

When climbing hills are you changing down the box as it slows down? If so, only change if the revs drop below 1,800 rpm.

Cheers,

4k...

This is a diesel, low revs, as Adz says change more like 2.5k.

Diesels like to stay slow and work hard, because they run relatively slow this is one of the reasons why they last so long.

Thanks for that guys!

I was really only trying to make a point - i dont rev over 3k normally, but my point was that i dont have any power in low revs, and therefore have to rev in excess when changing up the gears. Sorry for mis-informing you guys!
What is the likelyhood of the turbo being broken? i have had the intercooler pipes off, and it turns freely...
Any other tests i can do to see if the turbo is ok?

Thanks in advance.

Josh

Joshd said:

What is the likelyhood of the turbo being broken? i have had the intercooler pipes off, and it turns freely...
Any other tests i can do to see if the turbo is ok?

Click to expand...

Unless it's belching smoke and chucking oil about it's pretty unlikely it's the turbo itself, more likely to be the intake piping has a hole in it somewhere and you're not getting full pressure at the cylinder end. Sometimes splits only open under pressure, so you might not see them in the piping while stationary - by that, I'm not recommending climbing into the engine bay while it's moving!

Only way to check properly would be with a calibrated boost guage and watch it closely while someone else drives the car up a steep hill at full throttle in top gear - if the boost pressure climbs to max (i.e. about 1 bar) but you start to lose pressure quickly after that then there's likely to be a split that opens under pressure. If you don't get max boost pressure it's either down to a clogged intake somewhere - change the air filter and clean out the intake piping or a more serious blockage, like an intercooler full of oil , on the high pressure side of the turbo.

I don't know if there's a way to check the boost pressure at the manifold on these engines, someone else might know - would be a useful diagnostic aid if you can.

I'd check my air filter first, if that's ok I'd get the pump timing checked by someone qualified to do it next and then start worrying about whether my turbo was stuffed (unless it's chucking oil about and smoking like a crackhead)

Cheers,