DB18/2 low compression

[Mark Bullen]

Steve, thanks for the information.

The strip down is nearly over, just the rocker oil feed, exhaust manifold (release from the head)and head bolts left. The 20 to 30 minutes (from the Conquest manual) has been exceeded but only 1 washer has disappeared onto the floor and proving elusive. So far all the bolts have come undone well, nothing too seized and liberal amounts of WD40 have worked.

The block was very full of sludge and although running clear now I suspect more will be dislodged. Hopefully tomorrow I will be able to identify if a major head rebuild is required, a full engine rebuild (bore gauge ready) or just a thorough clean of every thing, replace rubber pipework, lap the valves and check flatness before reassembling. All the other pipework and removed bits will be cleaned, the debate is clean and repaint, or clean and have patina.

[Db n j]

Mark, you are correct in saying that there will be more sludge. Access is best through the waterways on top of the block because you can get behind the individual bores. The lowest point is the water drain at the left hand side of the block, so remove pipe, and keeping rodding til water clean.

Fingers crossed

[Mark Bullen]

The head is off and a cause of lack of compression is very obvious. The gasket is missing a chunk between 3rd and 4th cylinders. Not quite sure what could have caused such a large failure. The bores look in pretty good shape and will be checked for roundness and taper. Slight ridge at the top but might just be carbon build up. Lots of rodding has gone on in the block with the tap out as well so will need to flush through again.
Going to strip head and inspect valve seats, after doing a quick leak test, then run a straight edge over it all after cleaning up the faces.
Have noticed tappets feel really good sliding fit in their bores but some are a struggle to pull out, is that normal? At least one has some surface pitting, not sure if this will clean up or need a replacement.

I was lucky enough to borrow and engine hoist and a kind friend to lift it out. Awkward rather than as heavy as i thought. The main challenge was getting the legs under the lower suspension arms.

[grahamemmett]

It's a common failure I'm afraid.
Use a new style head gasket
https://www.ebay.co.uk/itm/202510003923 ... Swll1Ww0JH

[Mark Bullen]

Graham, thanks yes that's the one I have awaiting fitment.

I'm slowly stripping the head, lots of visitors interested in seeing inside a partially stripped engine has slowed me up a bit. The valves and seats will all need recutting. There is a small circlip that looks like a fail safe which sits in the undercut in the valve, does anyone know if they can be reused?

In an earlier part of the post there was talk of oil seals, I don't burn oil, but there is some slight play but I'm not sure there is time for replacement guides so seals might be an alternative, does anyone have previous experience of what they have fitted.

[Mark Bullen]

Head off and being checked and skimmed. A rough check with a straight edge suggested there might be a slight warp. Valves and seats a mess, lots of leaking so they are all being recut. I managed to find a recommended local engineer and it should be finished next week.

Anyone fitted inlet oil seals, what 'off the shelf' fitted?

All the bits are being cleaned. So far;

Heater pipe has a pin hole, but within the hose section which is being replaced anyway so probably can get away with it until some welding or replacement made.

Inlet manifold has some porosity on a flange face, not sure it will be a problem but might try and find a suitable filler. I'm sure there was a post recently about a suitable material.
What is strange and I can't find a picture anywhere to clarify is that at the radiator end of the jnlet manifold there is a gap in the dividing wall, about 5mm x 5mm which links both internal sides of the water flow. I'm hoping it's intended but can't think of a reason why it would be necessary unless it's some kind of flow balance? I'd post a picture but incompetence has set in.

Does anyone have a source for the engine paint, a light green colour. I might as well tidy up the head whilst it's off!

Oh and I'm still rodding and flushing the block, amazing amount of crap still coming out. Compressed air is a wonderful thing.

[Db n j]

Thanks for the update, very interesting.

No idea about circlips or oil seals.

The gap at the end of the inlet manifold is normal. If the manifold is rotten maybe get a replacement - Graham has one I think ?

David Beales sells the paint, but I’ve seen so many shades over the years, that any pale green will do just fine.

[Mark Bullen]

Head is back, amazing turnaround from a local company. It's all clean, painted and rebuilt. They skimmed it by 10 thou/0.25mm so hopefully it will now perform correctly.
Will there need to be shims under the rocker pedestals to compensate?

The correct colour paint has also arrived so some cleaning on all bits and a paint brush should make it look Daimler grey/green good, in parts.

I've been chasing threads, and the head studs have been particularly challenging, clearly some wear and significant build up in the threads, especially around the failed gasket, has resulted in a bit of thinning. Nuts seem to run up and down ok and with a set of studs at £140 i hope they will be suitable. I'm going to see if there are any more cost effective options available or does anyone have any alternative suppliers?

Hopefully it's the start of the home straight and I'm probably being a bit pedantic in cleaning threads, pipes etc.

[NickDeAth]

It's never pedantic cleaning threads, it makes it so much easier to reassemble.

Nick

[Mark Bullen]

Today involved finally removing all the cam followers to check and clean them. Some were easy, some a complete pain. A variety of levers and finally all were free. The running fit was good but really difficult to extract, no obvious lip in the block though. There is significant pitting on a few and also on the camshaft, clearly there will need to be a bigger rebuild in the future. I can only assume some dirty oil and or oil starvation during its resting periods.

Has anyone had any experience with grinding the cam followers and how much depth of hardening there is?

Any rescue attempt will only be temporary but at least might help prevent even more damage. I'll rebuild with assembly lube so at least there should be some cushioning with the camshaft.

Thread chasing continued and at last painting some parts ready to refit, including the rocker cover, tappet chest and head in green/grey Daimler made it feel. Shame some numpty used a BSF bolt in the manifold, hopefully there's enough good thread to hold it when the new bolt arrives as I really don't want to have to helicoil.