Author Topic: Advice needed - engine tightening up - help - tips  (Read 14535 times)

Offline nigeldtr

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Re: Advice needed - engine tightening up - help - tips
« Reply #90 on: 30.08. 2009 22:17 »
Quote
is the camshaft only fed when the pressure release valve opens
opposite, valve redirects whatever is left after crank gets it's oil dose.

Nice pressure gauge mod, just some quick thoughts, you are reading the pressure after feeding the crank and may get a very low reading, still everything will be ok (or plain bearing is very worn and leaking, if you get a very high reading I'd think the big ends\plain bearing are not fed properly!)

Hi and thanks for the comments.

The pressure take off is below the release valve so in theory, this should be the same pressure as at the main bearing and is really the pressure acting on the release ball. All depends on what pressure the release valve opens. Which I will find out tomorrow. I have not really lifted the revs yet, so prehaps the pressure will increase when I take her for a run. All interesting stuff!
1951 Golden Flash (engine now rebuilt) 1953 M21 a pain to start and 1961 GF that is turning into a black hole!

Offline nigeldtr

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Re: Advice needed - engine tightening up - help - tips
« Reply #91 on: 31.08. 2009 10:06 »
Hi John,

I have just carried out a few tests and found that by lifting the revs the pressure went up to 50 psi and then held there. This seems to be where the relief valve is opening. To double check, I slackened off the release valve spring retaining nut and could lower the opening point down to 40 and 30 psi. When tight it is operating at 50 psi. From these results, the pump seems to be doing its job. I will check it again once I get out on the road and can see what the pressure it stabalises at.

Nigel
1951 Golden Flash (engine now rebuilt) 1953 M21 a pain to start and 1961 GF that is turning into a black hole!

Online chaterlea25

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Re: Advice needed - engine tightening up - help - tips
« Reply #92 on: 31.08. 2009 22:27 »
Hi Nigel,
That sounds Better!!
Let us know how the road testing goes
In the photo of the cylinder and piston you have the brass feeler (shim) measuring the clearance at the top of the piston (or is going all the way down??)
Clearance should be measured at the bottom of the piston at 90 degrees from the pin

Cheers
JohnO R
1961 Super Rocket
1963 RGS (ongoing)

Offline nigeldtr

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Re: Advice needed - engine tightening up - help - tips
« Reply #93 on: 01.09. 2009 19:24 »
John - really appreciate the feedback!

so,  running on SAE 40 the engine starts and goes upto about 50 psi when the revs are lifted a little from tickover (relief valve opening). Once the bike has been driven for about 10 mins and she is getting hot, the pressure slowly falls away as the viscosity drops, infact gets down to about 20 psi at which point the release valve will never lift and send oil to the camshaft. After the initial start, I assume there is plenty of oil in the trough to keep things lubricated at least for a while - untl the next cool start? I live in German and it is currently about 30C so I am going to change to SAE 50 and see how we get on. I have no issue about buying a new oil pump (or perhaps better an oil cooler?)*smile* however, I suspect that even with a new pump, the oil pressure when the engine is hot never gets high enough to open the relief valve?

I appreciate a  high capacity pump will shift more oil and perhaps improve the pressure but do you or does anyone else know what the"hot" runnning pressure should be (I assume greater than 50 psi to open the relief valve, however, for a hot, journal bearing engine, this figure seems impossible?).


Regards

Nigel
1951 Golden Flash (engine now rebuilt) 1953 M21 a pain to start and 1961 GF that is turning into a black hole!

Offline nigeldtr

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Re: Advice needed - engine tightening up - help - tips
« Reply #94 on: 01.09. 2009 19:40 »
In the photo of the cylinder and piston you have the brass feeler (shim) measuring the clearance at the top of the piston (or is going all the way down??)

John, the shim went all the way down the bore and was at 90 degrees to the pin. The seized side took a lot of work as there was a high spot half way down! In the end, both bores were a nice sliding - push fit.

Regards


Nigel
1951 Golden Flash (engine now rebuilt) 1953 M21 a pain to start and 1961 GF that is turning into a black hole!

Online chaterlea25

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Re: Advice needed - engine tightening up - help - tips
« Reply #95 on: 01.09. 2009 21:46 »
Hi Nigel,
It looks as if there is either wear in the engine plain bearings or in the oil pump,
or a combination of both???
My Fathers old grey Ferguson behaved like your BSA!! 0 psi when the engine was hot *sad2* *sad2*
You could try running the engine for a little while, with the timing cover removed when hot
you should be able to see if the oil pump is leaking (a lot??)
This is a messy test!!!!!!
There are a couple of suppliers of either iron or alloy bodied pumps

Another issue can be if either the fibre washer under the front mounting screw is either missing or too thick!!
What I do is make a gasket like an A65 one that extends forward to include the front screw.
have a look at this as well.  http://www.srm-engineering.com/technical/wet-sumping-problems

Dont complain too much about 30 degree temps!!!
It looks like winter is on the way here in Ireland!!! after we have had the wettest summer on record!!!!!
Regards
John O R
1961 Super Rocket
1963 RGS (ongoing)

Offline alanp

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Re: Advice needed - engine tightening up - help - tips
« Reply #96 on: 02.09. 2009 15:51 »
Weather-wise, Chaterlea is right. However, what the Atlantic clouds don't drop on Ireland it off loads the rest on SW Devon. That's why we're both green but fed up!  Roll on next riding season, it can't be worse.
Member of the 'Last of the Summer Wine Club - Jennycliff'.

Offline nigeldtr

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Re: Advice needed - engine tightening up - help - tips
« Reply #97 on: 02.09. 2009 19:16 »
The weather was part of the reason for me moving from Manchester to central Germany - the only problem is that it is often too hot to go out  *smile*.

Re the SRM info, I will have a closer at look but I note the tests we done at 21 C with 20 WT oil not really engine temperature or recomended oil? I would also love to know how and what, the pressure drop test and the "running" tests where tested against, a valve which was openened to give a restriction at 50 psi then closed for the drop test? If I get time, I will give them a call and ask.

Tomorrow I will pop in the SAE 50 and do some more testing.

PS don't doubt that their pump is super, I like comparisions to be more "lifelike" though perhaps there would be no difference?

Regards

Nigel
1951 Golden Flash (engine now rebuilt) 1953 M21 a pain to start and 1961 GF that is turning into a black hole!

Offline nigeldtr

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Re: Advice needed - engine tightening up - help - tips
« Reply #98 on: 04.09. 2009 18:17 »
I swapped the oil for SAE 50 and found the relief valve opening almost as soon as the engine started ie just above tick over (tick over showed 40 psi). However after about 10 mins running, the pressure slowly started to fall and final held at  10 to15 psi for the the rest of the run.

I spoke to the guys at SRM and they explained the test process and seems perfectly valid running on a ?thin? oil to show up the weakness. After a good discussion, it seems that in anything but a new engine, the oil pressure will not be high enough to open the relief valve once the oil gets hot hmm!

Ok, a lot is dependent on the main bearing wear otherwise oil rushes out here and drops the pressure however, any engine with a bit of wear will not be oil tight here! It seems that the camshaft gets it dose of oil when the engine starts from cold or cool, and this is topped up from the rocker oil running down. If this is the case then long runs, like motorways etc are the death of the camshaft? Seems that a leasurely run with a few stops to let the oil cool and then set off again is the best ? I think this known anyway  *smile*

I would love to have some other comparisons with others with oil gauges but this seems to be a little rare!

Nigel
1951 Golden Flash (engine now rebuilt) 1953 M21 a pain to start and 1961 GF that is turning into a black hole!

Online Triton Thrasher

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Re: Advice needed - engine tightening up - help - tips
« Reply #99 on: 04.09. 2009 18:47 »
There must be a minimum hot oil pressure quoted for your bike.  I don't have a manual to hand, but it will not (surely?) be 15psi at road speeds!

I'd say you have worn bearings: main bush, big ends or both.

Online chaterlea25

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Re: Advice needed - engine tightening up - help - tips
« Reply #100 on: 04.09. 2009 20:44 »
Hi Nigel,
Looks like the next step is as I suggested, a short run of the engine with the timing cover off (when hot)
to see how much oil is passing (leaking) at the pump
Remember what I said about the fibre washer!!
It would certainly be a first step before a complete engine strip
Regards
John O R
1961 Super Rocket
1963 RGS (ongoing)

Offline nigeldtr

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Re: Advice needed - engine tightening up - help - tips
« Reply #101 on: 05.09. 2009 16:18 »

Well, I am am now coming to the conclusion that the main bearing is worn and dropping the pressure or pump is too weak or leaky. When I had the barrels off, I checked the big ends and they are fine. I tried to move the crank in the main bearing but at the time could see no excessive play. I took the timing cover off and fired her up but with rush of air from the crankcase I could not really see where the oil, running around, was coming from.

For info, I was out today for a short while and measured the oil temperature as the pressure dropped. At start, high oil pressure and release valve is opening (the return pressure is so high that it actually causes a few leaks around the rocker spindles).

Air temp today 20C, so ideal for the engine and rider.

Oil straight SAE 50.
Over 55/60 psi at 18C (cold engine)
35psi ? 40C
20 psi ? 50C
15 psi ? 55C
12 psi ? 60 C
10 psi ? 65 C ? no further reduction after this.

To me the oil temp seems fine but the pressure  drop is a real pain. From what I can see from the viscosity charts, a 3 fold increase in temperature (from 20 to 60) brings about 10 fold drop in viscosity! So with lower viscosity I need to move a heck of a lot more oil. So the problem could be pump capacity or shot main bearing leaking too much.

The next step is to remove the pump strip and check and also check the main bearing for wear and then have another scratch of the head ? I'll keep you posted.
1951 Golden Flash (engine now rebuilt) 1953 M21 a pain to start and 1961 GF that is turning into a black hole!

Offline nigeldtr

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Re: Advice needed - engine tightening up - help - tips
« Reply #102 on: 05.09. 2009 18:18 »
Had a spare hour so took off the timing cover and pump! The main is worn and will need replacing  at some time (not before winter). From looking at the pump, the engine has failed at some time and dragged debris into the return and feed of the pump. The feed side being particularly badly scored. I have attached pictures. Also looks like the wood worm have been at the body as there are plenty of holes around in the casting - for you John, I thought you would like these re your earlier comments. I will order a new pump Monday. I will flush out all the oil ways and oil tank and fit an oil filter, would prefer to put it in the feed side though to protect the pump. I presume it would have to be primed to ensure it flows freely.

Pics 2 and 3 feed, 5 and 6 return.

Nigel
1951 Golden Flash (engine now rebuilt) 1953 M21 a pain to start and 1961 GF that is turning into a black hole!

Online RichardL

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Re: Advice needed - engine tightening up - help - tips
« Reply #103 on: 05.09. 2009 18:56 »
That is interesting stuff and, obviously, very revealing. I would like to hear from John if that is the kind of porosity he had in mind. Those "wood worm" holes look like they could be the result of corrosion. I am looking forward to this new bit of knowledge.

Richard L.
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Offline rocket man

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Re: Advice needed - engine tightening up - help - tips
« Reply #104 on: 05.09. 2009 20:55 »
i see thats a case ove irish woodworm  *smile* at least youve
found somthing