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Discussion Starter #1
Hi folks,

My first post as new owner of '55 plate with 123k miles.

Thanks to all the threads I have read on here, I have dived straight in and embarked on changing thermostats (running temp 65-69deg). At the same time, I suspected the EGR valve would need a clean, since the power seemed a little flat, so I have just removed that and am horrified at how bad it looks inside. I am going to try soaking the valve body in brake fluid and scrape away as much as possible, but there is also a huge build up of crud around the entry to the inlet manifold and I am worried that if I disturb this, bits will end up going into the engine.

Any advice would be gratefully received - I was hoping to get it back together today (working outside).

Here are some pics showing the state of affairs:-
 

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Personally? I'd take the manifold off when you can leave it for two days, then follow the caustic soda method. It's the only worth while way to do it - whilst that off then you can tackle the EGR.

EGR if you have time is worthwhile to obviously sort your issues out, I'd also clean the pipe feeding it from the intercooler, its easy enough to unclip from the bottom.
 

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Looks bad ....
I would certainly remove the parts before cleaning them - you don't want that crud getting into the engine
 

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Thirded, remove the inlet manifold prior to cleaning.

Be careful soaking things, the Throttle valve has an electronics unit bolted to it, similarly the EGR has a rubber diaphragm controlled by a vacuum, you don't want those filling up with fluid.
 

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Jesus,by the looks of that crap it wasn't too far off letting go into the intake!!!!
As said though,best option is remove the manifold and do a caustic bath,remove all the little gaskets and map sensor and anything attached to it.
 

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I wonder what would happen if that crud got into the engine - i reckon it'd disappear pretty quick assuming it wasn't a lot?
 

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Discussion Starter #7 (Edited)
Thanks for the input guys.

I gave the EGR valve a scrape with a screwdriver and the crap turned out to be fairly soft. Actually, within a few minutes most of it had come off. A load of WD40 and kitchen towel later, it looked much better.

Couldn't resist seeing what the stuff in the manifold was like, and managed to scrape the worst of it outwards. Some must have dropped inside, but I got Henry hoover in there afterwards. Most of the stuff seemed to turn to a powdery soot when scraped, so I am hoping that any bits that went inside will just burn as they pass through the cylinders. My basic logic is trying to persuade me that the DPF will catch any muck before it reaches the cat.

Hopefully, having replaced the knackered EGR thermostat, the DPF may at last be able to do a regen and burn away all the crap.

Darkness stopped me finishing the job, but I will report back tomorrow with an update on the results.
 

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I wonder what would happen if that crud got into the engine - i reckon it'd disappear pretty quick assuming it wasn't a lot?
Be interesting allright if any of the valves caught a lump of it as they were closing.
 
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Discussion Starter #9
Thinking about the reduced inlet area due to the amassed crud, I worked out that the original 50mm bore of the inlet gave an area of approx 20cm2. The crud reduced the bore to about 35mm, which meant the inlet area was reduced to about 10cm2. Now I'm getting excited about a test drive tomorrow - if I haven't buggered it up. Previously the car ran fine at low revs, but didn't really accelerate with any urgency on full throttle.

Perhaps too much wishful thinking, but there was also a slightly erratic idle on warm up, as if it was sometimes missing on one cylinder every couple of seconds.

Anyway, this is what the EGR valve looked like before it went back on:- DSCF7175.jpg
 

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good work Mr Fingers!! interested to see if it cures your issues :) - I'd defo plan to do the caustic bit though, you think that inlet was small, wait until you see the ones from the manifold into your engine!

adber - any ideas what this decoking does that garages offer, I'm interested in how they clear the gunk actually in the head without damaging the valves...
 

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Don't get me wrong, I'm a petrol head and they raise their own sets of problems, low or high mileage. My diesel is on 150k now and the coke is nowhere near bad enough to cause issues in the head, just curious as if its a cheap process then i might eek out more mpg :)
 

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Discussion Starter #13
An update on the sooty deposits. They are gone for the time being - hopefully a fair few thousand miles longer. Actually, the job of degunking the crap which was visible in those pictures was dead simple, and the difference it has made to throttle response is fantastic!

I was nervous about how the engine would complain about ingesting bits of that nasty stuff, but after two of three pushes of the start button it kicked into life and was purring contently within a minute.

Thanks for the encouragement. I know the correct procedure should involve removing the inlet manifold, but this has confirmed to me that the decoke process is definately worthwhile.

I have only driven the car for a hundred miles since owning it and this was an impulse job which I couldn't resist while doing the thermostats (which is another story that I suppose should form a separate thread).

While I'm rambling on about my new baby, exhaust fumes are slightly noticeable in the car when it's running and stood still. The exhaust manifold area looks uncleaned yet not blackened, except there is a lot of oily black deposit on a pipe flange connection. Can anyone advise a simple way to check if this is actually the dreaded exhaust manifold problem?
 
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