The HTP has been getting more  and more tractor-sounding over recent weeks, to the point where I had to do something about it.

Seemed like it was coming from near the front, so I blamed the flexi in the front pipe, even though it is only five years old. Sadly, popping a new one on didn't make any difference, so that was a waste of money (only £30-odd from ECP though).

 

Decided to dig deeper yesterday, and investigate EGR and then exhaust manifold gasket if the EGR looked intact. It did.

 

Bit of a mission getting the manicat off these! Can't get to the manifold nuts with the heatshield in place, can't get the heatshield off without removing the lambda sensor, still can't get the heatshield off without moving the main rad fan holder bracket. Nearly couldn't get that off 'cos of a stupidly rusty torx screw that threatened to round out. Then you've got to get down below to disco the front pipe, then you go to pull the thing off and find there's still two more sodding screws down the back, T45s with really rubbish access, especially the one on the A/C compressor side.  No straight line path for anything unless it was just the right length to not foul one of the A/C pipes, and narrow. Got there in the end.

 

At least it was all worthwhile, so far anyway, as there was clear evidence of leakage outward and downward past both sides of the gasket at the pot 3 end.  Thought I'd spotted a hint of leakage towards the EGR valve once that was off and out the way, but I wasn't sure until the manifold finally came off (during half time of the footie).

 

Two photos of the awkward access bolt holes (note how they are barely even visible from the front, and one of the gasket, inside face:

 

 

Edited 9 August, 20187 yr by Wino

Now I've just got to work out what to do about the non-flatness of the manicat mounting face.  Tried flatting it off on some wet-and-dry but it wasn't even tickling the pot 3 end, when I stick a straight edge across pot 1 and 2, there's a good half-mm gap at the pot 3 end. 

It passes MOTs with flying emissions colours, so reluctant to replace, but the steel of the mating face isn't all that thick, so not sure how much re-profiling it makes sense to try?

 

Here's a fairly poor photo, pot 3 on the left:

 

 

 

 

Will get some better pics tomorrow.

Edited 8 July, 20187 yr by Wino

Here's a much clearer one:

 

 

Would have thought a new gasket should have enough 'squash factor' in it to take up 1/2 mm gap?

 

Edited 8 July, 20187 yr by TMB

Tricky, however grab a cheap 300mm alloy spirit level and use double-sided sticky tape to attach a strip of abrasive then level the face with it until you've just hit pot 3 all the way round then polish it up with some fine abrasive stuck to the level. Voila.

9 hours ago, TMB said:

Would have thought a new gasket should have enough 'squash factor' in it to take up 1/2 mm gap?

 

 

Yeah, I expect it would.  Not sure whether that manifold flange was like that when it was made, or has warped with the runners over the last 157k miles. If the former, then the new gasket will surely last until the next major work is required, if the latter, not so sure.

 

7 hours ago, sepulchrave said:

Tricky, however grab a cheap 300mm alloy spirit level and use double-sided sticky tape to attach a strip of abrasive then level the face with it until you've just hit pot 3 all the way round then polish it up with some fine abrasive stuck to the level. Voila.

 

Thanks Sep, I'd been rubbing the whole thing face down on a sheet of (oily) wet-and-dry stuck to a granite chopping board, but it is a bit unwieldy.  Have given it to a machinist mate now for assessment/advise.

Knowing him, I'll have it back flatted beautifully by lunchtime.

6 hours ago, Wino said:

Knowing him, I'll have it back flatted beautifully by lunchtime.

It didn't quite go like that. He said it's well worth de-banana-ing it, but way too awkward to hold on a mill.

So it was all my own sweat that's got me here:

 

!

 

Haven't worked that hard in ages!

 

Edited 9 July, 20187 yr by Wino

Very impressive!

How did you actually do this Pete?

I found a piece of chipboard kitchen worktop with a nice smooth/flat surface, about 400mm long by 80mm wide, kicking around in my shed. Made a nice sanding block, reasonably comfortable in the hand.

Started off with 80-grit wet-n-dry, oiled. Once I'd used up all the sheets I had of that, I changed to 120-grit, 'til I ran of that... etc.  I've got a sequence of pics I could put up later.

Desk fan pointing straight at my shirtless body, iced water by the litre, holding the thing with my left hand while sanding in imaginative random patterns with my right.  Took about an hour and a half.

Good stuff, I can imagine how much hard work it must have been but you got the result in the end.

 

Is it back on the car or are you still recovering?

No, not yet. Waiting on various replacement nuts and bolts. The missus is away so there's no time pressure.

Cool