New (to us) C250 W202 with a few Qs, Inc. EGR Question

[doddles]

We just bought a saloon C250 W202 last weekend and I'm going through what it needs doing. Not a lot, just the usual stuff, fuel filter, Orings, handbrake, etc. Oil change, oh and not forgetting new windscreen (no windscreen cover on our insurance policy).

Now, the EGR valve on the side of the alloy tube part of the intake pipework is literally unbolted. It's just rattling around next to the alloy pipe part fixed to the head. I've just had a rummage around for some bolts, but I either didn't have the correct thread, or some kind fellow has saved me the hassle of stripping the threads and done it for me.

I guess I'm losing boost pressure? My 2 options would seem to be, either find the correct size bolt and fit it properly (albeit, blanked off while I'm at it), or helicoil it, find the correct size bolt and fit it properly, or alternatively, get a short length of tubing of the same diameter as the intake piping and remove the alloy part altogether, or at least modify it so I can use it as a bracket for the replacement pipe.

I'm surprised it's driving as well as it is, but I guess the turbo is just over working to compensate for the loss of boost pressure.

 

[Tinkerer]

OK, so I have no clue as to the size of bolts that should be fitted but would guess at 8mm std thread and would suggest that if these look correct you go with these. I think it will be a threaded brass insert in the manifold so you will have to be very careful as there will not be a lot of 'meat' left. If it is like my CDI then totally defeating the EGR will throw up a plausibility error with the MAF and then trigger limp home mode and I am a little surprised that it is not doing this already. Good luck

 

[doddles]

Thanks for that, I'll have another rummage around or nip to screwfix.
I think it's possible to disable the egr on the old mech diesels due to no MAF, but I'll give it a whirl anyway and see what happens.

 

[guydewdney]

The old 250 you can delete the egr, the 300 of the same vintage throws a wobbly due to the implausiblity issue above.

 

[doddles]

Screwfix did the job Re the bolts. M8, went for slightly too long though, so will pack them a bit with a couple of washers. Bought 35mm, probably more like 30mm or even 25.
I read that a 3/4" copper end cap works to block off the EGR, so got that too and just waiting for it to warm up a bit.
Definitely picking up quicker with the EGR semi-re-attached. Can't wait for it to be properly sorted.

You can feel it dumping the valve on the turbo on long hills at the minute (at least until semi-sorted it today). I assume it wasn't reaching target manifold pressure and bypassing the turbo in case something is wrong with it. Had similar with an old vauxhall cavalier where it was losing boost via a damaged gasket, so wasn't putting the extra fuel in, so wasn't making the expected boost, so put less fuel in, less boost... etc. etc.

 

[91dm]

I've blanked the EGR on my C250, no error codes or lights. I blocked it directly at the exhaust manifold, the 3/4" cap I think is what I used as well.

 

[tim.100]

I've blanked the EGR on my C250, no error codes or lights. I blocked it directly at the exhaust manifold, the 3/4" cap I think is what I used as well.

Try and block it invisibly, as EGR deletion is going to be a MOT failure next year, IIRC.

 

[doddles]

In the end, I've got a bit of ally tubing to replace the egr/intake part temporarily while I get the thread drilled, tapped and helicoiled. It wouldn't torque up, the previous dafty had indeed stripped the threads.
I'll be blocking the egr invisibly and putting it all back later. At the minute, the orings are having to take priority.

 

[doddles]

EGR successfully blocked off and all put back together properly. Managed to tap the egr/intake part and use longer bolts. 22mm copper end cap worked a treat.