crankcase pressure

[dillyman]

Another problem for the experts!

I fitted a new front transverse silencer box today on my 44 because the old one was blowing noisily. Result success - but the previous din was masking another blowing noise from the engine - not exhaust I hope.

Trying to locate the source I removed the oil filler cap and found to my surprise that there is considerable pressure there going Huff - huff - huff in time with the engine. Is this normal? If not what is amiss? The engine runs well revs and ticks over with no problem. I remember that a 33 which i used to own once filled the whole engine bay with oil when I forgot to replace the filler cap - probably the same symptom. The huffing ceased when the cap was removed.

My garage lads opine that the crankcase pressure is sufficient to blow past the crankshft oil seals and that is where the huffing emanates from. Can this really be so? What is the cure if fault there be?

Best regards in hope - Marcus H.

[daf44]

hi marcus.

check the breather pipes are clear as well.
blocked pipes will also cause pressure in the crankcase.
another possible is worn piston rings. a compression test will tell but on a twin cylinder that size i would expect some loss of power as well. if it is running ok then you are probably in the clear here.

if you have enough pressure to pass a crankshaft oil seal you want to try and cure it fairly soon, as if pressure is passing the seal, SO CAN OIL.
i lost a nice beetle engine this way. not on the crank oil seal, but the pressure blew the seal on a push rod tube under the piston and blew the oil with it.

on a car this old the most likely is the carter valve is jammed with gunk or the pipes are full of it. or both. easily cured if this is the case.

keep us informed.

paul44


ps. where did you find a tranverse silencer box?? i could do with one myself as mine is held together with gun gum and hope.
i need to find one or rebuild mine soon.

[spunkymonkey]

Paul, there's one on for a 33 on Fleabay at the moment. Not sure if they interchange, but guessing they'll adapt better than anything else might!

I've been watching it quietly but can't really justify it as a "sit in the shed" spare if it's needed elsewhere. Finishes 9:55 pm today. If the link doesn't works search for Daf 33 front silencer:

cgi.ebay.co.uk/DAF-33-1962-74-FRONT-SILENCER-AND-INTER-PIPE_W0QQitemZ360039723758QQihZ023QQcategoryZ108797QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

[dillyman]

Paul - Got my exhaust transfer box from exhaustsuk.com in Sheffield. Phone no. 01142440999. He advertises in Classic car weekly to which I subscribe.

Thanks for suggestion re pressure- I had arrived at the same thought myself after posting query but have not yet had time or inclination to check! Too cold! Oil is present at engine front end too! Haynes manual has no mention of Carter flap valve of course though it does mention the breathing system en passant.

John - thank you too for input. I will comment further in due course.

Best regards - Marcus H.

[spunkymonkey]

Also a little concerned about crank-case pressure with ours now. Took it out for a little (unofficial) road-test a couple of days ago and noticed there seems to be quite a bit of the old blue smoke. Idles pretty smoothly (without the battery light flickering ) and seems to have fine performance.

But, pulled the oil filler with it running today and there seems to be quite a lot of (pulsing) pressure blowing out of it. I've never tried this with a horizontal twin before, and I'm assuming you're bound to get some as the pistons are moving in- and out- at the same time as each other.

But, assuming the worst for now, what's the situation like for rings / pistons for 33's now? Would I have any hope at all of tracking any down or would it be a case of finding a donor car?

[spunkymonkey]

Thanks for that reassurance, John. Hoping it's down to the thing standing / having short runs for so long. Would give it a dose of Redex through the plugs but the bores are pointing the wrong way & tipping the car on it's side might be a tad excessive

In fact, I would have assumed that completely if it wasn't for the amount of pressure that seems to blow from the oil filler when removed. In any "normal" engine I've known it'd be a sure sign of ring / bore problems but I guess two pistons moving into the crank case together is bound to pump a little air out of an open filler cap

[daf44]

hi there.

with regards to redex in flat engines, pour lots into the plug holes. put cloth in the holes to stop too much coming back out and turn the engine over a few times. this spreads it around in the bores. always worked on the old beetles. then leave for 10-15 minutes and start up the car. it may smoke for a minute as it burns of the redex but should clear quite quickly.

the other thing to try is thicker oil 20/50 or similar for older cars.
this and wynns/STP should help with the blue smoke as well.

if all else fails remember that these do not have emissions tests and as long as the car behind you can still see where he is going it will probably still pass an mot anyway.

good luck

paul44

[spunkymonkey]

It's a fair comment about the emmissions, John - besides, when they realise that Global Warming has got it wrong, they'll be grateful to those of us driving high-emmissions cars to help combat Global Cooling.

They'll drop the price of fuel to encourage us all to burn as much as possible and slap punitive tax on people who insist on driving "gas-sippers" with no regard for the environment. Of course, none of this may happen for quite some time, but a couple of centuries from now someone will bring up this post and see that it was all predicted. I'll become as famous as Nostradamus, and our little (soon to be) creamy-pinkish-greeny-yellow Daf will be bought by the Galactic Transport Museum as a priceless exhibit.

Nurse, is it time for my pills yet?

[dafdaffer]

I have found that the little aircooled lumps have quite a bit of heavy breathing! i once was driving down the road and i got the most tremendous rattlingi thought that one of the heads ha fallen off, it turned out that the filler cap was loose and was chattering, quite scary,

on my 1969 daf 44 i had one of the sets of rings brake up, it did give quite alot of warning as it was like one of the red arrows for quite a while, i had a low millage engine and decided to remove the piston from it, i took off the barrel to find that the compression rings had broken in half on this on as well, i decided what the hell and put the other piston in instead, the 5000 miles that i did after was fine!, i do however have a set of brand new standard piston rings for a 33/44/46 if ever they are needed by anyone.

Paul

[dillyman]

Reflection suggests that Paul is quite right about heavy breathing flat twins. Many years ago, as a young flat dweller in South Kensington I seem to remember...............................

As to my Daf 44 - I have checked the 'Carter' valve and pipe below. So simple! I can blow through it all with ease so think it is fine. Now have oily lips.

I guess that it can't possibly be blowing through the front crankshaft oil seal. The huff still continues at tickover only. It is not round the oil filler cap. Huff seems to depart when engine revved. I shall ignore it until something gives way!

As to destroying engines - I have successfully destroyed an 850 engine. Having travelled for several miles at maximum speed on a local motorway there occurred a loud scream swiftly followed by an even louder bang and silence. After recovery and investigation I found that the motor had seized solid, broken the crankshaft and wrenched out all the retaining bolts from the flywheel! Repair to the car was effected by scrapping the motor and inserting another from a scrappie. Anyone else suffered such adisaster?

Marcus H.