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930 General Work inc Heat Exchangers


flatsix777

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I finally got round to sorting out a few issues before a trip down to Italy in early August. The aim was to replace the Heat Exchangers that cracked a while ago, find a missing 50bhp from the last dyno session, revisit an issue with the flywheel ring gear and change out the rear engine mounts. I’m about 3 weeks into it but well on the way now. 

I tackled the HEs first. 

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The pipes had all cracked just under the flanges which caused a little blowing until hot. A previous welding repair to reattached one of the towers after a half shaft parted had also corroded badly. I had the n/s one off in 2006 to replace the charge pipe and this came off OK just using oxy to heat the fasteners. I had replaced 2 studs and all others were good. The stainless nuts I used worked great and no issues with gauling.

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The fasteners on the other side, which I think had been on since new, had corroded terribly. I tried welding a bit in to the barrel but but even with heat and an impact wrench could feel the stud giving. I decided to cut ithe nuts off. I dremmelled them and then, with heat, was able to drift then off. Worked great and all studs were serviceable. 

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Lastly I gave the charge pipe and wastegate a light refurb. 

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More to follow.

David

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When I changed the clutch in 2014 I the high torque starter I fitted in 2007 had damaged the leading edge of the ring gear. I was in a rush and didn’t have a replacement so flipped it around. I expected to find the same result but whilst worn more than it should be it’s not too bad. Not easy to photograph with an endoscope:

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The starter I fitted had quite a shallow pinion relative to the WOSP unit I just bought . Also 7 rather than 9 teeth which I still haven’t quite worked out. I was going to drop the motor and fit a new ring gear but am thinking the deeper pinion will help and the wear might not quite warrant it - not sure really.  Still deciding what to do.

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That’s as far as I’ve got. 

David 

 

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I was looking back through my photos to see if I could count the teeth on my WOSP starter but could only find the weight.

Good work on the exhaust removal. What a ball ache of a job. Interesting that you went for stainless studs instead of the brass VW jobbies. I had galling issues with stainless fasteners really quickly on my exhaust so changed back to sacrificial soft nuts. 

 

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When I served my time as an apprentice mechanic, brass manifold nuts were quite common, no corrosion and no problem with removal. That would be my preferred combination; stainless studs would be ok but the galling issue often comes up, there are anti-galling pastes on the market, but over time and with the heat I guess the effectiveness would decrease. How about stainless studs with brass nuts?......thoughts?

David

 

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Stainless is like cheese when it comes to fasteners that are doing any work.

Google search M8 'K' nuts these used to be available in brass or copper but usually copper plated these days. They still work well on manifold studs. Motor X guys use them by the bucket and are available in big bags for not a lot of £. 

Would recommend these for the accessable studs with a nickel based anti seize compound. I think they may also work on the hidden studs if fitted with a thin wall 1/4 drive socket.

From a personal experience the key to easy removal is a program or regular (12 months best 24 months max) removal, clean and anti seize compound.

 

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I decided that the ring gear was serviceable and so didn’t pull the motor. The WOSP starter is big improvement on my previous hi-torque unit and is hopefully kinder on the ring gear teeth. 

I lost some horsepower a while ago so have been trying to pinpoint the issue. My last dyno pull was only 285 bhp which was down on the previous 327. Nothing obviously wrong but I did notice my throttle rod was fouling the hard line to the turbo oil pump and I wasn’t getting WOT. Struck a cord as a flaling halfshaft took out quite a few things near to the  rod so could have clattered it too. With a new rod the clearance issue disappeared and full movement was restored. I’m pretty certain this is where the 40bhp disappeared but time will tell. 

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MoT on Friday so time to get it back together. 

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David 

 

Edited by flatsix777
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  • 2 weeks later...

Running through the Grimsel and Furka passes today. Heavy rain but some great scenery in the clouds. A long delay on to the Euro Tunnel got temperatures very high causing a restart problem in Calais but otherwise running great. 

Cheers

David

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