Jump to content

No turbo boost? Could it be a wastegate issue


DiscoMagic
 Share

Recommended Posts

I was driving along in my '97 300tdi and sudden as you like suffered a dramatic loss of power, it feels for all the world like there is no turbo boost on the car.

I had a split intercooler hose about 5 years ago and although they all looked fine this time I've changed them for silicone ones. I've also taken the opportunity to fit a non EGR top hose.

My next thought, after checking the turbo spins freely by hand, was a split intercooler so rather than fart about pressure testing it I got a meter of 50mm ID hose and joined the turbo to manifold bypassing the intercooler. Still just as flat.

Things get a bit more techie now, expect it is now possibly a wastegate problem. Has anyone had similar problems to throw some pointers to me please?

The linkage appears connected on the wastegate but need to wait until tomorrow and it's cooled to check it further. Will check the turbo to injector pump pipe too in case that's splt. I suppose I should get a turbo boost gauge too but just holding my hand on the turbo hose there felt to be as much pressue as on my brothers pickup by comparison. If the wastegate is partially stuck open would that create these symptoms?

I must admit I keep thinking I can hear something blowing but my brother who very rarely goes in this car can't. I know the vehicle better but it might be me wanting (?) to hear a problem.

The only other point of issue is that it had a new cam belt about 500 miles back along with full service including fuel and air filters. With this in mind she sounds fine running up with head under bonnet so I don't think the timing has slipped.

Many thanks in advance.

Link to comment
Share on other sites

The most likely cause is the pipe between the turbo and the injector pump. It is a little black plastic pipe about 6mm or so in diameter which comes off the back of the turbo, runs round the back of the engine and goes on to the injector pump. Function is to "tell" the injector pump when the turbo is on boost to increase the fuelling. If it isn't connected the engine performs like it hasn't got a turbo on!

Another related possibility is a split diaphragm inside the injector pump (much the same effect)

I have seen 2 or 3 with this problem I suppose and its normally the pipe come off one end or the other, which would go with the sudden loss of power.

A distant possibility is that the turbo impellor shaft has sheared between the two sides of the turbo, never seen it on a LR engine but I have heard of it happening, highly unlikely but worth checking I suppose to rule it out!

I thought if the wastegate jammed you usually ended up with too much boost but I've never seen one jammed so not sure.

Link to comment
Share on other sites

Thanks BogMonster

The car is 10 miles away so I can't run out to it at the moment but I know for certain that both ends of the turbo/pump pipe are connected so I'll have it out to check or bypass it with a new bit in case it's split.

If it's the diaphragm is that an easily replaceable part?

Link to comment
Share on other sites

i had a similar problem to this. The pipe from the intercooler looked fine but it turned out it had delaminated so the inside was collapsing block off air flow.

Link to comment
Share on other sites

Yes, very easy, four screws to take the cap off the compensator unit, the diaphragm is under that so you lift up the rubbery bit, wiggle it around and pull gently and it will pop out, careful not to lose the plastic collar off the shaft, there will be a loose spring under the diaphragm as well. Note the orientation of the "ding" stamped into the centre metal bit of the diaphragm before you move it, as it is critical for the fuelling that the diaphragm is positioned in the same way when you refit it, though you can also fiddle with it for more power, see tech archive for details :)

Worth checking the pipe off the turbo as V8camel says, just to be sure, only takes 5 min. The ones I have seen it has been inconsistent though, sometimes it is blocked other times not, depends how it distorts as the turbo spools up.

Another easy check is to squeeze the top intercooler hose tight between your fingers and then rev the engine hard, you should feel the pressure in the hose if the turbo is working.

Edited to say the diaphragm is easy but it ain't a LR part so if it is split it is off to a specialist or a breakers yard for a replacement...

Edited by BogMonster
Link to comment
Share on other sites

A friend told me the top hose should go almost rock hard but mine was nowhere near. I felt some pressure but not a massive amount.

I'm sure the turbo is blowing - as per the highly technical hand over hose test - just maybe not to required pressure.

I've been too busy today to spare any time on it so I'll have a crack over the weekend. I'll check the pipe to injector pump and if it's sound and clear I know the local firm of diesel injection specialists so I'll see if they have a diaphragm to fit.

Link to comment
Share on other sites

A friend told me the top hose should go almost rock hard but mine was nowhere near. I felt some pressure but not a massive amount.

I'm sure the turbo is blowing - as per the highly technical hand over hose test - just maybe not to required pressure.

I've been too busy today to spare any time on it so I'll have a crack over the weekend. I'll check the pipe to injector pump and if it's sound and clear I know the local firm of diesel injection specialists so I'll see if they have a diaphragm to fit.

Take of noise deadening cover, and look for oil around between the inlet manifold and cyl head indicating a blown gasket my last one did this.

You will not get full boost at a standstill even revved flat out.

Worth checking Les,s suggestion as i have also had the small plastic pipe split on the M4 uphill and i thought the engine had stopped, talk about gutless.

Lynall

Link to comment
Share on other sites

Jammed wastegates usually jam open against something and this would give no boost until the rev's got up. if it was a sudden loss of power i would agree with bog monster that chances are the pipe that runs to the injector pump has split of the diaphragm inside the pump has split. Get a boost gauge on a check for boost and then check the diaphragm.

Link to comment
Share on other sites

Well it will now be Monday before I can attack the turbo again due to unforseen weekend commitments, thanks for all the advice.

Will check the turbo/injector pump pipe, get a boost gauge and check the diaghragm in that order. Just hope one of these shows the way forward......

I'll post back my findings

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...

Important Information

We use cookies to ensure you get the best experience. By using our website you agree to our Cookie Policy