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DB18/2 low compression

Mark Bullen
Posts: 219
Joined: Mon Feb 15, 2016 1:07 pm
Location: Wiltshire

Re: DB18/2 low compression

Post by Mark Bullen »

A massive thank you for all the information and ideas, both here and by email. I had a very good conversation with a recommended engine builder who gave freely of his time even though I advised it was unlikely i could justify a full rebuild, at least I understand what can be done with a budget cost.
I spent a windy bank holiday Monday using a really simple device to pressurise the cylinders. A cost effective version of leak down testing.
The good news was it showed that the cylinders with good compression didn't leak air anywhere (even pushed the cylinders down from TDC) and those with low compression definitely indicated a leak across the bores. What was interesting was that cylinders 2 and 5 which had pretty good compression show some evidence of a leak.
My next job is to flush the block with core plugs out, radiator etc. and get replacements and gasket set ordered. Hopefully when I remove the head it will be nothing more than a gasket failure and it can be rebuilt quite quickly with the advice and documents I have been provided with.
Further updates to follow.

Brian-H
Very Wise Man
Very Wise Man
Posts: 1095
Joined: Fri Aug 09, 2019 6:04 pm
Location: UK

Re: DB18/2 low compression

Post by Brian-H »

Mark Bullen wrote: Wed May 05, 2021 10:00 pm I spent a windy bank holiday Monday using a really simple device to pressurise the cylinders. A cost effective version of leak down testing.
If you're able to tell us without having to kill us afterwards, what was the simple device ?

Mark Bullen
Posts: 219
Joined: Mon Feb 15, 2016 1:07 pm
Location: Wiltshire

Re: DB18/2 low compression

Post by Mark Bullen »

This was the device 'kweiny Engine Air Valve Holder and Cylinder Leakage Testing Assistant Tool Fit with M12 or M14 Thread'. I spent ages looking for something i didnt knw the name of and suddenly it appeared on Amazon

Bob Frisby
Posts: 33
Joined: Sun Feb 21, 2016 5:30 pm
Location: Boise, Idaho USA

Re: DB18/2 low compression

Post by Bob Frisby »

Chiming in a bit late here, but I fully agree with Stan Thomas. I'll bet "dollars to doughnuts" that you have a blown head gasket, and these two cylinders are just trading air. That's the way it was for me on my DB18 Empress, which had those exact symptoms.

The fix is straightforward, just remove the head and replace the gasket. I did have trouble pulling the head off the studs. Took quite awhile, using penetrating oil, hammers and winches.

But the question arises as to what else to get done while you're at it. I did a full and proper valve job, with re-cut seats, re-cut (lathed0 valves, proper lapping, and a very thin re-surfacing of the gasket surface. I had no other problems, so I stopped there, and have been happy for a dozen or so years since.

Bob Frisby
Boise, Idaho USA

Mark Bullen
Posts: 219
Joined: Mon Feb 15, 2016 1:07 pm
Location: Wiltshire

Re: DB18/2 low compression

Post by Mark Bullen »

Again thanks for all the input and advice. The strip down has started, albeit a bit tentatively. There might be plenty of sludge in the system as having drained via the bottom hose (I had completely forgotten the tap I had replaced in the radiator a couple of years ago), I refilled with water and a sludge remover and it only needed just over a gallon rather than the three the manual stated.
It occurred to me that I need to record the process as despite lots of detail rebuild and technical documents being available, there doesn't appear to be anything in writing to advise the best strip down process. A Haynes manual approach would be useful as I think the last engine strip I did was in the early 90s on a golf gti.
If anyone knows of a strip down document I would gladly receive it and update with pictures if necessary. Every time I look I see more bolts to remove.
In essence
Manifolds but leave connected to down pipes
Manifold to thermostat housing
Thermostat housing
Tappet cover
Block drain tap-proving a bit challenging as it's also connected to the manifold
Carburettor to inlet manifold for clearance to remove manifold from studs
Rockers, push rods etc.

I can only see 2 core plugs on the side of the block, on the manifold side that are accessible. Once everything is off I intend to remove these, flush, prod and dig out so that finally I can remove the head and confirm the problem.

Hopefully the parts due this week will have arrived for the rebuild, assuming nothing more serious than a head gasket. We have a local car show mid June and a school prom a couple of weeks later so that's my challenge. If it's more than a head gasket then i think we'll be out of action for a bit longer.

Brian-H
Very Wise Man
Very Wise Man
Posts: 1095
Joined: Fri Aug 09, 2019 6:04 pm
Location: UK

Re: DB18/2 low compression

Post by Brian-H »

There are quite a few manuals to choose from on the db18.org website https://www.db18.org/manuals

There's also a seller on ebay who sells many other manuals on a DVD https://www.ebay.co.uk/itm/Daimler-Cons ... 4319604130 for an incredibly reasonable price. I don't have this DVD because I've collected most of it in original paper form over the years, including the Daimler Conquest Workshop Manual, a full workshop manual which is useful for the engine in the DB18 & Consort. Check out what he says about problems he's having with ebay , making selling it so cheaply on ebay pointless, so maybe contact him and ask how to obtain it https://www.ebay.co.uk/usr/virtuallystamps

Mark Bullen
Posts: 219
Joined: Mon Feb 15, 2016 1:07 pm
Location: Wiltshire

Re: DB18/2 low compression

Post by Mark Bullen »

Brian, thanks for the tip off, I contacted the gentleman earlier and had a 400MB file winging its way to me a few minutes later. I'm busy going through the documents.
It's strange but nearly every manual i find wherever it is available has exactly the same information and wording :D . Generally it is comprehensive on engine removal and exact details of the engine. So far nothing significant on head removal other than leave the manifolds on the down pipes. I guess it was a fairly common activity when the cars were newer and mechanics would have known and been confident, and not requiring of an explanation. Haynes manuals have helped for those of us without formal training. Anyway I'm happy to learn and will probably get to the end of the process and understand what i could have done differently.
The positive news was the gaskets arrived today earlier than expected.

Brian-H
Very Wise Man
Very Wise Man
Posts: 1095
Joined: Fri Aug 09, 2019 6:04 pm
Location: UK

Re: DB18/2 low compression

Post by Brian-H »

Haynes often has some issues or even errors. On one 80s car I had, it described how to renew the cambelt - but with the engine out of the car. With the engine in the car (a transverse engine) the engine mount on one side had to be removed as well as other things, none of which was in the Haynes. Even the tensioner came off differently. The Haynes was only good for setting and locking the cam and crank positions before cambelt removal.

That Daimler Conquest Workshop Manual is superb, for cylinder head removal see Section A Part 2, page 8. I guess that having the paper version makes it easier to find stuff ;) Note that on that page in the Conquest workshop manual they say to remove the head with manifolds still attached (after separating the exhaust manifold from downpipe), then remove manifolds on the bench. It is possible to remove the manifolds first, leaving the exhaust manifold attached to the downpipe - as described very briefly on page ii of the May 1951 Motor Trader supplement (possibly the Haynes of its day). What intrigues me is the 15 page Daimler Consort workshop manual that he mentions - I might contact him myself.

SteveJay
Posts: 14
Joined: Mon Jan 27, 2020 6:39 pm
Location: Bath

Re: DB18/2 low compression

Post by SteveJay »

Hi

I'm in the process of making this data free on my website but I'm busy with a new kitchen - its currently on wetransfer - https://we.tl/t-5K6RTpg9wC

Ebay changed the payment rules - and i now make less than 50p on most of the manuals - and although I give the money to charity its not worth my time for 50p! The daimler set is probably an exception but help yourself _ i Will get these available asap free

help yourself!

All the best

steve

Brian-H
Very Wise Man
Very Wise Man
Posts: 1095
Joined: Fri Aug 09, 2019 6:04 pm
Location: UK

Re: DB18/2 low compression

Post by Brian-H »

Many thanks Steve

PS looks like "British Repair Manual - Cars" was the Haynes of its day

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