Disco 2 Overboosting

Disco 2, TD5, manual.

Two mornings in a row driving home from work I've had the turbo exit elbow blow off and limped the rest of the way home at about 30mph.

Am I right in thinking that this is probably just a sticky wastegate modulator causing overboost?

I'm on night shifts at the moment so don't really have the time or inclination to fix it until I'm off again so using the wife's car. Just looking for some likely causes to check out when I'm off work.

Is it a silicon hose? I've read that they are not a grippy as the standard rubber hoses. Could it be a blocked intercooler. I'm sure the knowlegable will be along soon.
Griff

This happened to me during our Christmas hols in the Dales. Fixed it in no time by taking the, yes, silicon, hose off cleaning it and the bits it attaches to to within an inch of their lives, then REALLY CAREFULLY refitting. The trick for mine seemed to be to get the hose really fully onto the next pipe, i.e. properly over the lip, then ensure the Jubilee clip stays the other side of the lip while tightening it with a socket and small ratchet.
The hose is new and it has stayed on ever since.
Previously i had tightened it partially on top of the lip, which is why it blew off.

DefenderPilot said:

Disco 2, TD5, manual.

Two mornings in a row driving home from work I've had the turbo exit elbow blow off and limped the rest of the way home at about 30mph.

Am I right in thinking that this is probably just a sticky wastegate modulator causing overboost?

I'm on night shifts at the moment so don't really have the time or inclination to fix it until I'm off again so using the wife's car. Just looking for some likely causes to check out when I'm off work.

Click to expand...

I do hope my previous answer made sense and you were not talking about another pipe, in which case once clarified we can help.
I have had the wastegate cause the fuel restriction to come on due to the engine sensing overboost. This was cos the nuts holding the wastegate actuator came off.

OK, yes I have silicon hoses but they've been on since the rebuild and have given no problems.

The pipe I'm talking about is the small elbow that joins the turbo outlet to the long metal pipe that runs to the intercooler inlet.

Also, I've done a code read and have an overboost code so I guess it definitely is overboosting.

DefenderPilot said:

OK, yes I have silicon hoses but they've been on since the rebuild and have given no problems.

The pipe I'm talking about is the small elbow that joins the turbo outlet to the long metal pipe that runs to the intercooler inlet.

Also, I've done a code read and have an overboost code so I guess it definitely is overboosting.

Click to expand...

Well as far as I can tell without a picture we are talking about the same elbow although it is only about 120 degs not a full 90 degs elbow. It is very short and connects the turbo outlet to, as you say, the metal pipe that runs forward and then, though another flexible to the intercooler.
When mine came off i could drive the car reasonably OK on the flat, it was climbing the steep hil out of Ingleton towards Hawes where i had to have my foot flat to the floor. But mine is an auto so it may make a bit of difference. I got no code to fix or anything, not that i have actually read the codes. Yikes!
It's driven fine ever since.
You're gonna make me plug my Foxwell in now!!!

DefenderPilot said:

Am I right in thinking that this is probably just a sticky wastegate modulator causing overboost?

Click to expand...

Some confusion here, the modulator is electronic not the valve which can be sticky but both can cause overboost just that it's completely abnormal that a hose to be blown for that cos once the overboost occurs the ECU cuts the fuelling. The only way to get such boost at that hose is to have a restriction between the turbo and inlet manifold but then there would not be an overboost fault code. You might have an overboost issue too but that hose is not supposed to come off in that case

sierrafery said:

Some confusion here, the modulator is electronic not the valve which can be sticky but both can cause overboost just that it's completely abnormal that a hose to be blown for that cos once the overboost occurs the ECU cuts the fuelling. The only way to get such boost at that hose is to have a restriction between the turbo and inlet manifold but then there would not be an overboost fault code. You might have an overboost issue too but that hose is not supposed to come off in that case

Click to expand...

Have to agree, I think there are two separate issues here.

I see. I meant the vacuum operated bit that opens the wastegate. Pardon my ignorance. That was going to be the first thing I checked. I can see I might have a bit more work to do then.

DefenderPilot said:

I see. I meant the vacuum operated bit that opens the wastegate. Pardon my ignorance. That was going to be the first thing I checked. I can see I might have a bit more work to do then.

Click to expand...

Disconnect the diphragm bit from the arm that opens the wastegate, check that it moves freely then reconnect it. If it is seized you have a problem but it ought to shift with a bit of persuasion. The check that the arm reconnects at the same place yuo took it off from, i.e. that you haven't accidentally shortened or lengthened the throw. on a typical TD5 there should be 13 threads visible between the actuator and the lock nut thing. ensure the diaphragm of the wastegate actuator is seciurely mounted on its two bolts.
The hardest part of this whole operation is getting the third bolt in under the turbo shield. It requires a bit of persistence.

I'll take the turbo shield off to do this.

DefenderPilot said:

I'll take the turbo shield off to do this.

Click to expand...

Well it is exactly the third bolt that holds it on that I am talking about, the one at the rear.
Unless a previous owner has left it off!
But yes it is maybe not possible to do the work on the wastegate without taking it off. I've never succeeded in doing anything while leaving it in place.
But if you unbolt the actuator you should be able to see if the arm moves easily at the turbo, in which case you can leave the shield alone. Unless you need to adjust the length of the rod.

Just thought I'd update this topic and throw out another question.

Long story short: the wastegate lever was very sticky and I was unable to free it up so I've taken the turbo off and fitted the original turbo back on. Problem solved.

However, I changed the original turbo because it was very worn and the shaft was a little bit stiff to turn if pressure was applied to the compressor wheel. I can live with it for now but I'm thinking about getting a new turbo.

What are people's thoughts/experiences with the cheap refurbished turbos you can get on ebay for around £200?

Something like this.

DefenderPilot said:

Just thought I'd update this topic and throw out another question.

Long story short: the wastegate lever was very sticky and I was unable to free it up so I've taken the turbo off and fitted the original turbo back on. Problem solved.

However, I changed the original turbo because it was very worn and the shaft was a little bit stiff to turn if pressure was applied to the compressor wheel. I can live with it for now but I'm thinking about getting a new turbo.

What are people's thoughts/experiences with the cheap refurbished turbos you can get on ebay for around £200?

Something like this.

Click to expand...

Thanks for letting us know the cause of the problem.
I am surprised that applying copious amounts of freeing off stuff, and wiggling it back and forth didnt't eventually free it off.
Anyway.
Best of luck with a secondhand or whatever one.

It's a strange one. It was perfectly free when I fitted it but now there are 3 places where it sticks fast. Also, there is a lot of axial play in the spindle so it's probably fubar.

DefenderPilot said:

It's a strange one. It was perfectly free when I fitted it but now there are 3 places where it sticks fast. Also, there is a lot of axial play in the spindle so it's probably fubar.

Click to expand...

If it is, you might as well strip it down to see what has gone wrong with it.
I'd like to see pics of what you find.
For some turbos I know you can get rebuild kits, dunno about this one.
In your position I'd be tempted by a VV type one, to give some extra oomph.

I chucked it in the back of the Disco I took it off. That was taken away today by it's new owner. I'm sure I have one tucked away somewhere from my old Defender. I'll have to see if I can find it and see what sort of state it's in. Probably similar as the Defender had similar astronomical mileage to the Disco. It'll do as an exchange unit probably.

The ECU is tuned by Storm Tuning and I have a bigger intercooler fitted. I'm happy with the oomph I've got with this setup. Performance turbos are very expensive. A nicely working standard one will do me just fine.

DefenderPilot said:

I chucked it in the back of the Disco I took it off. That was taken away today by it's new owner. I'm sure I have one tucked away somewhere from my old Defender. I'll have to see if I can find it and see what sort of state it's in. Probably similar as the Defender had similar astronomical mileage to the Disco. It'll do as an exchange unit probably.

The ECU is tuned by Storm Tuning and I have a bigger intercooler fitted. I'm happy with the oomph I've got with this setup. Performance turbos are very expensive. A nicely working standard one will do me just fine.

Click to expand...

Well, with that additional info.....
I'll keep my mouth shut.

Problem solved? Ah, it would seem not.

Driving the wife to work this morning I suffered abrupt power loss again. On getting home I did a code read and sure enough, I have an overboost code again, 20-02. It would seem I maybe had more than one problem. I've been doing a few google searches and came across this: http://www.discovery2.co.uk/wastegate.html

So that's next on my hit list before dropping money on a new turbo. For what they cost it's worth a try. In the meantime I'm going to bypass it and connect the wastegate actuator direct to the outlet pipework, as it is in the Defender and see what difference it makes.

Well, I've done the modulator bypass and been for a good thrash and what a difference! It's a completely different animal. Since I finished the rebuild it's always been a bit hesitant when you floor it with occasional lumpiness in the power delivery, which I had always attributed to the turbo. Now it pulls like a train, with smooth power delivery all the way through the gears and rev range. It would seem that the wastegate modulator is dodgy. I think I'm going to leave it like this as it's much better to drive now.