My (more than usual) sluggish 300tdi

**Flexual** · 23rd June 2013, 05:10 PM

Hi guys, I own a 300tdi disco with an auto trans and no engine mods. Recently I was driving up mount bawbaw. If you know the mountain, I was just driving up the finial 6km sealed road to the village, and its steep. I couldn't get it over about 30km p/h without sending the pyro into the 600deg range and eventually I got a transmission fluid temp alarm, so I pulled over, cooled it down and turned back.

Now I know these trucks are sluggish but this was REALLY slow. I had the auto rebuilt about 25-30k km ago and had the follow up service done on it so I'm hoping its not the issue... I had a quick chat with the mechanic who worked on it, his response wasn't overly convincing, saying that "its an old car and the transmission cooler cant really keep up, so I can fit a newer, bigger, better one for a fee". Now that may be worth doing anyway, but it felt like it just wasn't delivering any power.
It seemed to jump on and off boost (about 2.5-3k rpm in 2nd gear) which got me thinking that perhaps my injector pump needs a good tune or there is a turbo/intercooler issue.
I'm not very knowledgeable with cars so I'm obviously just speculating.

Some other general info :

On a mild incline, I can't accelerate beyond about 60-70k unloaded. (Me driving, one passenger with virtually no gear). I've only got a roof rack and a steel bar up front on standard size A/T tyres.

It's seems to need excessive time to warm up: Generally need to run it for 5mins or get the pyrometer up to about 80 deg on idle before it will pull away. Colder than that and it barely moves.

Fuel economy is average. 80L tank sees me through about 650-720 km with normal driving.

So, my questions are...

Does this sound abnormal?
If it sounds like I need a proper tune, is there somewhere reputable I can send it to get the injector pump, fuel system tuned? (I've heard good things about Clayton Diesel... )
Does it sound like a turbo/intercooler/plumbing issue?
Gearbox?

Thanks in advance for help/tips!

**Judo** · 23rd June 2013, 06:00 PM

I would start with some checks on intake air flow. Take the hoses off and look inside if they feel OK from the outside. Particularly between turbo and intercooler.

**wrinklearthur** · 23rd June 2013, 09:41 PM

With the over heating, I changed the radiator out with a new one after trying everything else and the new radiator fixed all the problems.
After a while ( 250,000 - 300,000 Klm's ) these radiators get a plaque build up inside the tubes that run through the radiator's core and that plaque is a very poor conductor of heat.

What Judo has said, check inside the hoses for any signs of them delaminating, wash the insides of the intercooler out with kero or similar, but make sure you get rid of any fumes before you hook it backup.

Is the transmission due for a new filter and fluid?

Fuel filter and the sedimentor may need servicing as they maybe restricting the diesel flow.
.

**Flexual** · 24th June 2013, 09:18 AM

Thanks for the replies.

Ill give the air intake and turbo plumbing a clean up and see how I go from there.

Trans fluid is fresh, had the box serviced last month, I'd assume the filter was done too but ill have to confirm that. Is that something I could do myself without having to lift the car up?

I have replaced, the sedimenter, pump, and injector pump and tank 2years ago, but haven't cleaned the sedimenter since... Perhaps ill do that! I changed the fuel filter last month.

I had a radiator core replaced 18months ago too along with some coolant pipes.

The more I think about this, the seemingly endless amount of causes becomes apparent!

Ill keep hunting!

**loanrangie** · 24th June 2013, 09:33 AM

I drove that same section of road in an 85 3spd auto rangie on gas and it really struggled to climb so i know what you mean, havent tried it in the disco and not keen to go back there again - its a mean bit of road.

**Judo** · 24th June 2013, 09:36 AM

My initial thoughts were that you have a problem (possibly air intake/turbo related), which in turn is causing a secondary problem of overheating. Low on power, poor fuel economy, high EGT's are what makes me think that. But I could be wrong.

Do you have the factory temp gauge? Or an after market one? Anything abnormal?

And have you noticed any smoke? What colour? Lastly, being that it's a new pump, was it set to ~factory fueling, or was it "tweaked"?

**Flexual** · 24th June 2013, 10:32 AM

Factory temp gauge, seems to behave itself. I've got a coolant level sensor alarm too, which hasn't tripped in yonks. There is smoke, it's light in colour and noticeable at idle, heavier under throttle. More throttle, more smoke.
The pump, as far as I know was set to factory, but it was done 3rd party so I've really no idea. Hence wanting to find someone who knows how to tune them properly.

**Judo** · 24th June 2013, 11:08 AM

Unfortunately the factory temp gauge doesn't mean much. Won't move off the normal middle mark until it's past hot.

While getting into 600*C EGT's while pushing the engine hard is not bad in itself, it should only be while pushing hard.

Originally Posted by Flexual

It seemed to jump on and off boost (about 2.5-3k rpm in 2nd gear) which got me thinking that perhaps my injector pump needs a good tune or there is a turbo/intercooler issue.
I'm not very knowledgeable with cars so I'm obviously just speculating.

(snip)

On a mild incline, I can't accelerate beyond about 60-70k unloaded. (Me driving, one passenger with virtually no gear). I've only got a roof rack and a steel bar up front on standard size A/T tyres.

These 2 points don't seem right. I have slightly bigger tyres that push the engine a little more, but a mild incline is not that bad. Most "mild" hills I can maintain close to 100kms/h. (Unless our idea of mild is very different).

Anyway, let us know how you go.

**Smokaharma** · 24th June 2013, 03:24 PM

My disco was sluggish but not to that extent untill I recently replaced all my brake pads and it turns out I had a heap of silicone sludge in my brake lines and it was causing the pads to rub just enough to slow the disco down. We got all the sludge out and obviously slapped new pads in after stripping and cleaning the calipers and hey presto more power and beter fuel economy.

**libertyts** · 25th June 2013, 04:47 PM

I had huge issue with keeping pace up hills and keeping the EGT's down at the end of last year. Turns out I had a small hole in the lower intercooler pipe, which grew larger up until I replaced them with pretty new silicone ones.

I now have no issues keeping the temp down and the speed up! That would be the first place I would look.

When you say smoke is visible on idle, do you mean on startup or literally while it's sitting there idling? If it's while sitting and idling... That's not normal and could point to too much fuel from the pump, the "smoke screw" will be the culprit here most likely. This over fueling will definitely cause high EGT's and possibly the sluggish performance if the over fueling is at the more extreme end of the scale.

Only problem with these pumps if you don't know a whole lot about them is it can be difficult to tune them properly after someone has stuffed with it. It takes a lot of trial and error and a lot of patience. The EGT gauge will help you immensely in this task though.

I will give you an idea of my temps at the moment, I have a 300TDI with the "smoke screw" uping the fuel input down low by a reasonable amount (3 turns I think, but suspect it had been played with by previous owner). Driving on the flat on suburban roads I sit around 240 to 280. Add a decent hill maintaining 60/70 kph in 4th will see it climb to around 320 to 380 if this hill goes for say 2 to 4mins.

At 90/100 kph on the flat I maintain 340 to 380. Add a mild hill will see it rise to about 360 to 410. A relatively decent hill will push it to about 420 to 480. If I am towing say my 750 kg trailer fully loaded the latter would push out to maybe 480 to 580.

Bear in mind these are average figures while normally maintaining speed or dropping at most 10 to 15% speed. I personally don't like going over about 320 day to day in the suburbs and about 420 on the highway. These figures "feel" right to me by the way it drives.

I'm going to have more of a play with my pump soon, just need a boost gauge first so I can fiddle with boost at the same time if need be.

I hope this helps,

Chris

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