losing boost pressure?

Thanks ChalesY, will prob just get some recon ones and replace them as they are selling them for £20 at my local dealers. - Engine needs rebuild as down on compression on one cylinder as well (you can hear it when you run it over as every forth compression is much faster than the other 3)

Steve - just be VERY careful here - most people who try adjusting wastegates get carried away - i have seen a 7.5 tonne lorry litterly dismanlte itself after the owner got slightly gready in the power stakes, and thought just one more turn!) - manifold started glowing, oil seals went on turbo, engine ran on its oil, oil runs out, con rod comes through crank case, engine blows up......... dont go above 18psi (20 ABSOLUTE max) and watch the manifold temp

stevedehtiar said:

hey all, just fitted my boost gauge plugged it into the threaded hole in the back of the inlet manifold, foot down to the floor in 5th gear im reading 0.8 bar(11.5psi)?? (im still getting a whooshing noise, but from nowhere obvious) im gonna try adjusting the waste gate actuating rod to get a bit more boost and see what happens..

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Go easy. A single turn on the wastgate actuator is about 1psi increase in boost. Dont twist the rod or it can tear the diaphragm. The problem you've got is that just upping the boost can make the engine run lean which means things tend to get hot. I'd say 18psi at the manifold is at the upper limits assuming your fueling is correct. You may need to play with injector pump which is way out of my league. Hence I have a TD5 where fueling is done on a 'puter. Overfuelling can be seen as black smoke but underfuelling is not so easy to see. Sounds silly to think of a diesel running lean like a petrol engine but the symptoms are similar without the pinking noise. ie. overheated valves, pistons, and manifolds.
If your engine is on its way out I'd leave well alone until you've got a replacement ready to go. There's no point in boosting it for max output as you'll just kill it quicker.

Shifty1962 said:

The problem you've got is that just upping the boost can make the engine run lean

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Now then how can you come to that deduction when it is a DIESEL ENGINE?

There is NO SUCH THING as a diesel engine running lean!

There is NO MIXTURE to be lean!

It ALWAYS draws in a full amount of air, but on light throttle only a little fuel is injected, whereas on full throttle it gets the same air but a whole lot more fuel.

I fear you don't yet see how a diesel operates, and what the effect of supercharging is on a diesel, whether by turbo or blower.

CharlesY

CharlesY please explain as I'd like to understand why this happens and what its called.

Maybe LEAN is the wrong word but turn your boost up, leave your fueling alone, and watch the manifold and turbo casing glow red, then orange, with the heat. It can't be because there is too much fuel being burnt in the manifold (because we have not changed that) so it must be because the available fuel is burning quicker and hotter due to more O2 available at higher boost pressures. The exact same symptoms as a lean running petrol engine.
I dont profess to be a "diesel expert" but I've seen this with my own eyes on several different diesel engines - some of which have self destructed. Turn the boost down again and exhaust temps return to normal.

i had a little play with end (turned it wrong way- ended up with 0.5 bar ) its pretty much back to where it was now.. gonna try and go the other way a turn (or two) and see if i can get closer to 1.0bar.. dont wanna go too mad- as the engine is in good condition, well serviced etc and the prospect of destroying it is a place i dont want to go..lol (i have been disconnecting the linkage off wastegate and adjusting then a 4mile roadtest to test..)

Mark the rod with tippex or some such then you can return to where it was if needs be.