466 Bedford motor

The hidden hazard of crap mechanics during the history of old motors is very real. To give an example I have a 10 litre Volvo motor which was taken out of service because it "made noises" says vendor. The exhaust manifold had overheated and let bits of shrapnel into the turbo, and little wonder because on dismantling I noted that the camshaft timing was two teeth out. The gear wheels are marked with dots and you would think no one would get it wrong. Further dismantlng revealed one low compression piston from a later model motor and a late type valve (mostly) secured with earier collets. It was only a matter of time before they let go but the overheating beat it to it. Big end bolts could be undone with 3/8" socket ratchet. All this and the motor was considered so good by vendor that he used it as an upgrade swap in his fleet!
A lot of those 466 motors are heavy on oil, sealing the rings seems to be an art with them and some recomend throwing abrasive powder down the inlet.

graham AGAIN
how is it possable i have head planed , valves done , and STILL GET AIR BUBBLES LEAKING OUT ?? This is probable worring me more than relining cyls , new pistons & rings ...
regards graham

Graham, was the head crack tested ?
I drove a KHM 70 Beddy many years ago that would drive around all day without overheating but as soon as you pointed it up a hill it would overheat.
Turned out to be a hairline crack not noticable to the naked eye
A couple of jars of irontite took care of it luckily.

Head was sent to "experts" and they did what ever they do .. invoice said " crack tested " Do old beddies get warped blocks easily or often I dont want to buy all new gaskets for 3rd time only to find bubbles along the join of block and head We MUST get it right this time .. one would think head repaired , new gasket , what could go wrong ? but we seem to be missing something
GRAHAM

graham AGAIN
how is it possable i have head planed , valves done , and STILL GET AIR BUBBLES LEAKING OUT ?? This is probable worring me more than relining cyls , new pistons & rings ...
regards graham

I'm a qualified Automotive Machinist (Engine Reconditioner) The possibilites are almost endless of reasons what your problem could be and something that a machinist should probably take a look at (not taking anything away from good mechanics! ) In answer to your question above. Even though your cylinder head has been machined and the valves refaced, it's still possible the top of the block is warped, the liner protrusion is incorrect, an incorrect head gasket has been used (or incorrectly prepared). The head bolts may be stretched, the head bolt holes may have $hit in them and prevent the correct tension from being acheived..

Was the head pressure tested/crack tested? It's possible to have cracks under the valve seat inserts that don't show up in a crack test, but will when pressure tested. When they are pressure tested they are filled with very hot water to simulate operating temperatures and then the water jackets are pressurised to 60psi...

Also a word of warning about running a bead of weld down old cylinder liners to remove them - A few years back a customer read up his workshop manual on his engine and decided to save a few dollars and do some work himself when stripping his engine. He read about running a bead of weld down the old line to shrink it, making removal easier. Well, unknown to him, there was two versions on his engine! 1 was a dry lined engine, and the other was one with integral bores (no liners at all)... Well, he ran beads of weld down his block that didn't have any liners! It didn't save him any money when it came to me repairing that stuff up! The moral of that story is to ensure the block actually has liners before cranking up the welder.

Best of luck with the Beddy
-Stu

Graham - Stu has given you more good info .. and yes, something is not right, that is still being missed, if you're getting combustion bubbles from between the head and block, even after head reconditioning, and a new gasket.

Yes .. blocks DO warp .. regularly .. and particularly after being overheated. This is why engine reconditioners who repair engines thoroughly, take engines apart to the last nut and bolt .. hot tank all major components .. check thoroughly for cracks .. surface grind mating surfaces .. and check crankshaft and camshaft bores for proper alignment.

The immediate answer that comes to mind for the air bubble problem is a warped block surface where the head sits.
However .. there are any one of a dozen other reasons, too.

1. Head stud holes not cleaned out, as Stu mentioned.
2. Incorrect tension on head studs.
3. Incorrect gasket that doesn't match the appropriate engine S/N.
4. Head has come from another engine with a different S/N, and your engine is a later S/N, and has a modified/improved block, that the earlier head doesn't match up to, correctly.
5. Incorrect piston or pistons for the engine, increasing compression ratio to substantially above specifications.
6. Incorrect conrods creating same conditions as above.
7. Incorrect fuel injection timing, leading to too-early fuel injection and too-high combustion pressures.
8. Incorrect injection pump settings, increasing the quantity of fuel injected above specifications.

These are just some of the possible reasons, off the top of my head. You need to do further disassembly, accurate measuring, and checking of all the above-mentioned scenarios, so you can gradually eliminate the possibilities, and find the source of the problem.

Cheers - Ron.

or even a sleeve that is moving in its bore

Graham, I had simular problems with my 466. I pulled it down and found a few broken top rings. It didn't seem to have damaged the grooves, so I cleaned it up and fitted new rings, and valves to the head, and all new gaskets. The pistons were not original Bedford pistons because they didn't have the second oil ring below the gudgeon pin. However I did everything by the book, and had a diesel fitter hone the bore. He honed it with very coarse grit.When I started the engine oil started to drip from the exhaust pipe just in front of the muffler.He said it would take up as soon as the rings bedded in.
Well it never, I tried all the tricks like making the engine work hard and pull for long distances up hill etc.
Nothing fixed it.
I found a supplier (Mr. Motorman) He had a set of Bedford 466 pistons and he made me up a set of rings
Top ring Chrome, next two standard cast compression rings, above gudgeon pin oil ring is same as cord ring( made up of about 5 steel segments and an expander , and the below gudgeon oil ring is a standard segment ring with the two rails cast spacer and the steel expander. Fully cast oil rings only seem to work if the engine is new.
I honed the bore with a much finer grit simular to what is used in a petrol motor.Fitted it all together filled the sump with BIMROSE first fill lube oil (bit pricy) but never used a drop in 5.000 k (Bimrose first fill is a special oil to bed rings into the bore)
I have just last week changed the oil to penrite 20W60 and the bedford is running beautifully and no oil leaks from the seals, (you will probably find the seals were leaking because of blowby causing a pressure in the crankcase , and it doesn't use(burn) any oil at all.
It is very important to get 24 good quality washers to fit under the head bolts, (i think the bolts do bottom out if the head or block have been resurfaced.)Get a pressure pac of "Hylomar gasket joining compound" from Repco or Super Cheap. Give the head gasket a real good coating until it is all blue, being careful not to rub any off while handling it. Have help to fit head so it fits on square and doesn't slide on gasket to damage compound. Tighten head to 75 ft lbs. Start at the middle and work to each end.Then go over again at 100lb then again at 105ft.lbs. When the engine has done about a thousand k. have the head bolts rechecked and pulled down to 105 ft.lb again.You will probably find a few not tight enough. This is what causes the gas leaks causing the little bubbles.


Mr.Motor Parts Ph.02 9739288 or 1800 812 354
Doug or Tim or www.mrmotorman.com.au
Bimrose oils www.bimlube.com.au
oil@bimlube.com.au
Ph. o7 49213800 Tom Bimrose
Cheers, Colin

mrmotorparts is the web name. He also has some Perkins 6354 parts and some inter stuff, lots of Leyland & AEC

graham back
looong story short .. n0 3 cyl valve was open on compression .. pushing unburnt fuil into exhust
NEW MECHANIC adjusted all valves / rockers . We have have driven 200 ks to Toowoomba all seems ok .. compression test showed 380psi to 400psi is that ok?
motor running around 90c with hilux ute A framed towing is that to hot or ok ? oil pressure down on before but im using 30 grade mono .. instead of 20/60
let me know what you all think
and thanks for your help
graham