MD22 sewing machine sound

Yngmar

Yngmar

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Been meaning to ask this for a while now. My MD22L-B makes a sewing machine noise, pretty much exactly like this (a much better recording than what I tried to do on my phone). It's more noticeable in idle than when under load, but that may be because the sound gets drowned out then.

I'm more curious than worried as the engine runs fine, but what might this be? Is it just the lift pump? Is it normal or a sign of impending doom. I do realize this is a bit like googling symptoms and then finding the most worrying disease to match them :eek:
 
I only listened to the first few seconds of the clip, couldn't face 8 minutes at my download speed on board, but it sounds like tappets to me. Quite possibly normal for the engine, but the clearance could be a little large.
 
If my sewing machine sounded like that would take it in for servicing!

You may be able to determine the source of the sound that interests you by using a listening stick.
 
Thanks everyone. Just had a peek at the workshop manual for checking/adjusting valve clearance. Seems quite a bit of a job on that engine. Manual demands some special clamps ("camshaft locks") to hold the camshaft in place while checking clearance.

Adjusting then requires removal of the timing belt, so I might as well replace that, and then removing the camshaft to lift the buckets and access the shims underneath them. So I need a set of shims. And removing the camshaft means I can replace the camshaft seals.

Sounds like I ought to (without any undue haste) gather all the bits for this along with everything else that makes sense to do along with it, such as a new timing belt and camshaft sealing rings. Has anyone done this valve clearance adjustment? What did you use for the "camshaft lock 885025" special tool (three of which seem to be needed, as depicted below)? According to the manual, those are required even just for checking valve clearance.

md22_camshaft_lock.jpg
 
Yngmar said:
Thanks everyone. Just had a peek at the workshop manual for checking/adjusting valve clearance. Seems quite a bit of a job on that engine. Manual demands some special clamps ("camshaft locks") to hold the camshaft in place while checking clearance.

Adjusting then requires removal of the timing belt, so I might as well replace that, and then removing the camshaft to lift the buckets and access the shims underneath them. So I need a set of shims. And removing the camshaft means I can replace the camshaft seals.

Sounds like I ought to (without any undue haste) gather all the bits for this along with everything else that makes sense to do along with it, such as a new timing belt and camshaft sealing rings. Has anyone done this valve clearance adjustment? What did you use for the "camshaft lock 885025" special tool (three of which seem to be needed, as depicted below)? According to the manual, those are required even just for checking valve clearance.

md22_camshaft_lock.jpg
Click to expand...

Crikey ..... I take back what I said above ..... that picture IS a bucket and shim camshaft!!!

I assume that it is not oil-pressurised which would be the next stage of technology so I cannot believe that you need any special tools to check the clearances. Just face the cam lobe away from the shim and measure the clearance.

Almost certainly you will need a special tool to remove the shim to check the size of the one already in the bucket to enable you to calculate the size of the replacement. You need to hold down the bucket whilst moving the cam lobe out of the way so you can extract/insert the shim. The alternative would be to completely remove the camshaft to gain access to all the shims but this is not normally the recommended procedure as the clearances, in theory, might have altered slightly when you re-fit the camshaft. However, I have done it this way and I reckon it's accurate enough.

Perhaps the clamps are used to relace the bearing caps so you can move the camshaft aside easily?

Richard
 
Sounds like a bit of overkill. I have measured and adjusted cam clearance on Alfa Romeo and Jaguar twin OHC engines many times without using anything like that. I would try checking clearances first without the device to see whether anything is necessary.
 
Looks like you need the clamps due to the upper cam bearings being part of the cam cover.

You can't really pre-purchase a shim set. You measure all of the clearances and strip buckets and shims, taking care not to mix any of them up. You then measure the shims and calculate what size shim is required, adding the thickness of the current shim to the difference between the clearance and what the clearance should be.

Usual procedure for a shimmed head would be, draw a grid with a row for each valve ;

1st column = current valve clearance.
2nd column = difference between current clearance and what is should be.
3rd column = shim thickness.
4th column = required shim thickness (sum of columns 2 and 3).

You can then look at columns 3 and 4 and see which existing shims can go where and order any shims that you don't have.
 
PaulRainbow said:
Looks like you need the clamps due to the upper cam bearings being part of the cam cover.
Click to expand...

Good grief Paul .... that would explain the inability to check the clearances without the special tools ...... but never, in my wildest dreams, have I heard of such a system. It doesn't bear thinking about that bolting down a cam cover would also include bolting down all the cam bearings in one casting when the cam is being held up at an angle under the cover by the lobes which are engaging with shims.

If your theory is right, that is one of the most user-unfriendly engineering solutions I have ever encountered! :(

Note to Yngmar .... I would not remove the cam cover until you have really studied the workshop manual or spoken to someone familiar with that specific engine. If Paul is right the cam will be pushed upwards by the valve springs as soon as you loosen the cover unless you get the crank/camshaft position exactly right and re-fitting it might not be as straightforwards as would normally be expected.

Richard
 
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My first thought would have been to check the clearances without the tool, but looking at the manual, it looks as though the upper bearings are part of the cover. A very unfriendly arrangement.

I'd make something up to do the job. Some bits of 1" x 1/4" flat looks like it'd do the job, with a bit of felt or fabric on the bearing surfaces to protect them.
 
PaulRainbow said:
Looks like you need the clamps due to the upper cam bearings being part of the cam cover.
Click to expand...

Yep it does. Thinking about it, without them, the cam shaft would just be pushed up out of place by the valve springs on whichever cams are pointing down. Richard, the buckets cannot be removed with the camshaft in place.

I've just remembered Stu Davies PBO article about rebuilding a Perkins Prima from an old Austin Maestro as a spare engine (which the MD22 really is, plus some fancy marine bits). In this he says about checking clearances:

VP sell special tools for the purpose, but I just got some 8mm bolts, nuts and washers and drilled a steel bar to suit so that I could put the bar across the bearings to clamp the cam in place and check the clearances.
Click to expand...

That sounds doable (thanks Stu!), as long as I make sure the camshaft is really properly held in place (else all the clearances measured will be worse than useless).

Also good point about reusing existing shims, hadn't thought of that. Still, given the scope of it, I'll let it sew for a while longer while I collect the parts, tools and willpower to tackle these jobs.

Cheers everyone!

Oh! I've just managed two better recordings with some processing in Audacity. The first one is from the engine room and you can hear the sewing sound, especially when throttling up. It stops when releasing the throttle until the engine is back down to idle speed.

The second recording is from the cockpit at the companionway (with engine room doors open), where the rest of the engine noise is more muted and the sewing machine sound sticks out more.
 
Suggest you contact skipper stu who is the guru on these engines having stripped and rebuilt them (as written up in PBO). He is in Portugal at the moment but has posted here recently.

Edit See you have found Stu already.
 
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Yngmar said:
Thanks everyone. Just had a peek at the workshop manual for checking/adjusting valve clearance. Seems quite a bit of a job on that engine. Manual demands some special clamps ("camshaft locks") to hold the camshaft in place while checking clearance.

Adjusting then requires removal of the timing belt, so I might as well replace that, and then removing the camshaft to lift the buckets and access the shims underneath them. So I need a set of shims. And removing the camshaft means I can replace the camshaft seals.

Sounds like I ought to (without any undue haste) gather all the bits for this along with everything else that makes sense to do along with it, such as a new timing belt and camshaft sealing rings. Has anyone done this valve clearance adjustment? What did you use for the "camshaft lock 885025" special tool (three of which seem to be needed, as depicted below)? According to the manual, those are required even just for checking valve clearance.
Click to expand...


Adjustment of valve clearances with this sort of overhead camshaft set up is something you would normally only do as part of a major, or at least cylinder head, overhaul.
 
VicS said:
Adjustment of valve clearances with this sort of overhead camshaft set up is something you would normally only do as part of a major, or at least cylinder head, overhaul.
Click to expand...

Agree. Although the process is tedious, unlike old fashioned push rod (or even side valve!) engines it is not a normal service procedure and would guess most such engines never need it.
 
Tranona said:
Agree. Although the process is tedious, unlike old fashioned push rod (or even side valve!) engines it is not a normal service procedure and would guess most such engines never need it.
Click to expand...

Checking clearances with every overhead cam engine I've ever worked on has been a 30 minute job which you could do on a whim if you felt like it and no more tedious than a pushrod engine. I've never seen one like Yngmar's before. :(

Richard
 
Yngmar said:
Richard, the buckets cannot be removed with the camshaft in place.
Click to expand...

But I've never said that. :confused:

It's only the shim you need to remove with the camshaft in place and I've done that on many OHC engines. Once you remove the shim you can either read the size on its lower side or measure its thickness with a gauge.

After that, it's a doddle.

Required clearance = 20
Measured clearance = 25
Current shim = 250
Required shim = 255

As you say, you need to measure all the clearances and check all the installed shims before you buy any new shims as you may well find that the 250 shim which you remove from this bucket is the right size required for another bucket .... and the 255 you need for this bucket is the removed one from a third bucket.

With judicious interpretation of the clearance range, the best I can ever recall is re-setting the clearances on a 16 valve DOHC engine and needing to buy only 1 new shim. :)

Richard
 
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RichardS said:
Checking clearances with every overhead cam engine I've ever worked on has been a 30 minute job which you could do on a whim if you felt like it and no more tedious than a pushrod engine. I've never seen one like Yngmar's before. :(

Richard
Click to expand...

There have been hundreds of thousands of these engines in use since the mid 1980s in both petrol and diesel form. Originally a BL engine for the Montego/Maestro/Sherpa. Diesel version was done by Perkins and then passed onto Volvo. The sandwich construction (shared with the smaller BL engines) was considered a good thing at the time and won design awards. Results in a very simple rigid cam carrier arrangement that does not wear. So regular checking not necessary.
 
Tranona said:
There have been hundreds of thousands of these engines in use since the mid 1980s in both petrol and diesel form. Originally a BL engine for the Montego/Maestro/Sherpa. Diesel version was done by Perkins and then passed onto Volvo. The sandwich construction (shared with the smaller BL engines) was considered a good thing at the time and won design awards. Results in a very simple rigid cam carrier arrangement that does not wear. So regular checking not necessary.
Click to expand...

All I said was that a generalisation that "an old fashioned push rod (or even side valve!) engine" is easier to adjust than an OHC engine is not correct. I'm not sure what your reply has got to do with that? :confused:

Richard
 
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