300CE WBX Repair

Big lumps of metals and spanners. Including servicing and fluids.

Moderators: Moderators, User administrators

Post Reply
User avatar
300CE
Posts: 2102
Joined: 16 Aug 2012, 13:05
80-90 Mem No: 12017
Location: Sidcup, Kent

300CE WBX Repair

Post by 300CE »

Well the engine has now been removed from the bus at long last ready for a gander at the possible reasons as to why she has been over pressurising. Removal was pretty painless, however, I am going to require a new exhaust as there were a couple of noticeable cracks once removed (to be fair it's a mild steel one which has been on there for about 9 years so it hasn't done too bad). Will be going the stainless route and put up a post in the wanted section shortly.

ImageUntitled by Justin C, on Flickr

ImageUntitled by Justin C, on Flickr

Unfortunately, I have completely mislaid my brand new compression tester so was not able to test the compression numbers prior to removal (I know I need a slap Paul!). I've posted up a couple of pictures of the ports on either side of the head - you can see slight discolouration on the first port on the right hand side compared to the other 3. This could possibly be leakage?

Left Side:

ImageUntitled by Justin C, on Flickr

Right Side:

ImageUntitled by Justin C, on Flickr

Present from Brickwerks (Gasket Set):

ImageUntitled by Justin C, on Flickr

Engine is now at my mates garage ready for strip down in the coming weeks so watch this space.
'86 DG, Weber Carb

User avatar
itchyfeet
Posts: 12385
Joined: 23 Jul 2007, 17:24
80-90 Mem No: 12733
Location: South Hampshire

Re: 300CE WBX Repair

Post by itchyfeet »

fingers crossed on the studs, heating the nuts helps and I recommend it even if it does bugger the plating its better than a snapped stud.
you want to be careful not to heat the valve springs, you can use a shield.

:ok
1988 DG WBX LPG Tin Top
1989 DJ digijet WBX Holdsworth Villa 3 Pop Top
itchylinks

User avatar
300CE
Posts: 2102
Joined: 16 Aug 2012, 13:05
80-90 Mem No: 12017
Location: Sidcup, Kent

Re: 300CE WBX Repair

Post by 300CE »

Cheers Paul, will deffo heat them up prior to removal and fingers crossed they’ll be ok. What do you reckon on that slight discolouring?
'86 DG, Weber Carb

User avatar
itchyfeet
Posts: 12385
Joined: 23 Jul 2007, 17:24
80-90 Mem No: 12733
Location: South Hampshire

Re: 300CE WBX Repair

Post by itchyfeet »

300CE wrote: What do you reckon on that slight discolouring?

to me looks like just one is clean
steam cleaned?, had the same when I had a cracked head
1988 DG WBX LPG Tin Top
1989 DJ digijet WBX Holdsworth Villa 3 Pop Top
itchylinks

User avatar
300CE
Posts: 2102
Joined: 16 Aug 2012, 13:05
80-90 Mem No: 12017
Location: Sidcup, Kent

Re: 300CE WBX Repair

Post by 300CE »

Hmm, not looking good then - Are they usually toast if the head has a crack or are they repairable?
'86 DG, Weber Carb

User avatar
itchyfeet
Posts: 12385
Joined: 23 Jul 2007, 17:24
80-90 Mem No: 12733
Location: South Hampshire

Re: 300CE WBX Repair

Post by itchyfeet »

A cracked head is toast but don't assume its cracked, if you have a compression seal leak, when you stop the engine sometimes the valves will be open and steam will get into the inlet, an indication perhaps that this is the one with the leak?
1988 DG WBX LPG Tin Top
1989 DJ digijet WBX Holdsworth Villa 3 Pop Top
itchylinks

User avatar
300CE
Posts: 2102
Joined: 16 Aug 2012, 13:05
80-90 Mem No: 12017
Location: Sidcup, Kent

Re: 300CE WBX Repair

Post by 300CE »

Aah, I see, cheers Paul - so in essence, it’s the clean one may be the leaky one! Will update with some pics once the heads are off for further info! :ok
'86 DG, Weber Carb

User avatar
itchyfeet
Posts: 12385
Joined: 23 Jul 2007, 17:24
80-90 Mem No: 12733
Location: South Hampshire

Re: 300CE WBX Repair

Post by itchyfeet »

This was a leaky compression seal, this is what you may find, you can see the discoloration at the top of the barrel sealing surface and the damage to the bore surface caused by water entering.

https://flic.kr/p/VVju6q" onclick="window.open(this.href);return false;
1988 DG WBX LPG Tin Top
1989 DJ digijet WBX Holdsworth Villa 3 Pop Top
itchylinks

User avatar
300CE
Posts: 2102
Joined: 16 Aug 2012, 13:05
80-90 Mem No: 12017
Location: Sidcup, Kent

Re: 300CE WBX Repair

Post by 300CE »

That does look a bit of a state - in the event it is like that, is it worth just replacing that one barrel/piston?
'86 DG, Weber Carb

User avatar
itchyfeet
Posts: 12385
Joined: 23 Jul 2007, 17:24
80-90 Mem No: 12733
Location: South Hampshire

Re: 300CE WBX Repair

Post by itchyfeet »

lets wait and see :ok
1988 DG WBX LPG Tin Top
1989 DJ digijet WBX Holdsworth Villa 3 Pop Top
itchylinks

User avatar
300CE
Posts: 2102
Joined: 16 Aug 2012, 13:05
80-90 Mem No: 12017
Location: Sidcup, Kent

Re: 300CE WBX Repair

Post by 300CE »

OK - started to take off and strip down the heads today. No drama's getting them off:

ImageUntitled by Justin C, on Flickr

ImageUntitled by Justin C, on Flickr

ImageUntitled by Justin C, on Flickr

ImageUntitled by Justin C, on Flickr

ImageUntitled by Justin C, on Flickr

ImageUntitled by Justin C, on Flickr

Seem to have located the source of the problem - the o ring seals on two of the barrels (one on each side) were not sealing properly due to poor condition and probably down to there being no anti freeze being used previously at some point in it's life:

Barrel 1

ImageUntitled by Justin C, on Flickr

ImageUntitled by Justin C, on Flickr

Barrel 2

ImageUntitled by Justin C, on Flickr

ImageUntitled by Justin C, on Flickr

All internals looked fine, with no heavy scoring or lips.

For now, cleaned up the heads and re-lapped the valves:

ImageUntitled by Justin C, on Flickr

ImageUntitled by Justin C, on Flickr

ImageUntitled by Justin C, on Flickr

ImageUntitled by Justin C, on Flickr

ImageUntitled by Justin C, on Flickr

ImageUntitled by Justin C, on Flickr

So, at the moment its looks as though i need two barrels and all will then be honed at my mates workplace. Piston's will also be removed as i'm going to replace the rings whilst everything's off.
'86 DG, Weber Carb

User avatar
itchyfeet
Posts: 12385
Joined: 23 Jul 2007, 17:24
80-90 Mem No: 12733
Location: South Hampshire

Re: 300CE WBX Repair

Post by itchyfeet »

The bad sealing you have shown is not compression seals but when the green o rings fail it allows coolant to get to the compression seals and degrade them.

worth inspecting the barrel top sealing surface and the head sealing surface in detail
also worth lapping the barrels into the heads with fine grinding paste.
1988 DG WBX LPG Tin Top
1989 DJ digijet WBX Holdsworth Villa 3 Pop Top
itchylinks

User avatar
300CE
Posts: 2102
Joined: 16 Aug 2012, 13:05
80-90 Mem No: 12017
Location: Sidcup, Kent

Re: 300CE WBX Repair

Post by 300CE »

itchyfeet wrote:The bad sealing you have shown is not compression seals but when the green o rings fail it allows coolant to get to the compression seals and degrade them.

worth inspecting the barrel top sealing surface and the head sealing surface in detail
also worth lapping the barrels into the heads with fine grinding paste.

Cheers Paul - do you think that the o ring failure could have been the cause of the problem? The more I think about it, the more I reckon it’s worth going for a set of new barrels and so I’ve gone for it and purchased some :ok
'86 DG, Weber Carb

User avatar
itchyfeet
Posts: 12385
Joined: 23 Jul 2007, 17:24
80-90 Mem No: 12733
Location: South Hampshire

Re: 300CE WBX Repair

Post by itchyfeet »

Personally I'd change rings too for the brickwerks KS ones, I know it's more money but piece of mind

https://www.brickwerks.co.uk/piston-rin ... dh-cu.html" onclick="window.open(this.href);return false;
1988 DG WBX LPG Tin Top
1989 DJ digijet WBX Holdsworth Villa 3 Pop Top
itchylinks

User avatar
itchyfeet
Posts: 12385
Joined: 23 Jul 2007, 17:24
80-90 Mem No: 12733
Location: South Hampshire

Re: 300CE WBX Repair

Post by itchyfeet »

your cooling system was pressurising right?

You don't get a compression leak from the failed O rings, it comes from a failed compression seal ( the metal rings)

the cooling system works at 1 bar the engine makes 9-12bar so if the metal rings have failed even a good oring won't hold 9-12 bar

the o rings are just there to keep coolant away from the compression seal.

that scratch on the right hand cylinder may well be what caused the failure.

Image
1988 DG WBX LPG Tin Top
1989 DJ digijet WBX Holdsworth Villa 3 Pop Top
itchylinks

Post Reply