VP MD202B - No compression

[Heckler]

Hi Stu, no the head has not been removed.

When I was talking about the problem in the yard, the timing being a bit out was the main suspect, timing gear casing was removed, and timing marks verified as correct. So I think it will either be spot on or 180 deg out

Found this, marks pretty straightforward,
View attachment 61183
However check that you have definitely got it on the right stroke by checking that No1 is on TDC on the firing stroke. That is why it is important to check that the valves are closed! By the looks of this diag, TDC is when the dot is at "quarter to" so set the gears as shown and with the rocker box off make sure No1 valves are shut. Then it is a case of checking that the pump is injecting at about 25deg before TDC.
Stu

 

[Jokani]

Thanks for the advice, hoping to take Friday off work this week, get to the boat and see if I can get it sorted.

Will report back.

 

[RichardS]

Richard
The guy has said he used the marks, he is still not sure if it is right, my way is the definitive way, no possibility off it being wrong. Like you, many years of experience, I took his remarks in to account when giving my suggestion!
Stu
PS Why mention decompressors when everyone knows that the md20X0 series doesn't have them!

C'mon Stu ..... Gary says in his post 10 that "he does not believe that there any TDC marks" on the flywheel or the crankshaft pulley .... so pray tell how he could have used them!

I think you need to "take his remarks into account when giving your suggestion".

As for "everyone knows that the md20X0 series doesn't have them", I cannot imagine why everyone who doesn't have an MD20X0 series would know that, which is why I attached the caveat. And please have mercy and don't say "Google it" as I've said many times that I don't Google but only give specific advice from personal experience .... everything else I qualify.

Richard

 

[AntarcticPilot]

Hi Stu, I bow to your superior knowledge, but how does the stop cable work on this engine?

The same way as it does on most diesels, by cutting the fuel off at the injector pump. And yes, I too was brought up with a diesel that was stopped by using a decompressor and was surprised to learn that few modern (post 1970s!) diesels stop that way.

 

[Heckler]

C'mon Stu ..... Gary says in his post 10 that "he does not believe that there any TDC marks" on the flywheel or the crankshaft pulley .... so pray tell how he could have used them!

I think you need to "take his remarks into account when giving your suggestion".

As for "everyone knows that the md20X0 series doesn't have them", I cannot imagine why everyone who doesn't have an MD20X0 series would know that, which is why I attached the caveat. And please have mercy and don't say "Google it" as I've said many times that I don't Google but only give specific advice from personal experience .... everything else I qualify.

Richard

Post 1 and 6?
Stop digging!

Stu

 

[anoccasionalyachtsman]

Thanks everyone for your help so far.



As far as I am aware there is not a de-compressor on the MD20x0 series.



Although I do not see how, I could have got them out of synch, at the moment this does seem seem the most likely cause as to why it will not fire



I do not believe that there are any TDC marks.

If I follow philwebbs's method and remove an injector to find TDC, then both valves should be closed. If not closed (this i why there is little/no compression) I can presume that I have the camshaft out by 1 revolution, so I would need to remove the intermediate gear spin the camshaft by one revolution, then refit the intermediate gear etc.

If the valve timing is wrong, it's the crankshaft you'll need to turn one revolution, or the camshaft one half.

 

[RichardS]

Post 1 and 6?
Stop digging!

Stu

Jeez ..... if I didn't know the difference between cam timing marks on the cam gear train and TDC timing marks on the crank assembly I'd not only have stopped digging but been buried years ago.

Keep reading post #10. :encouragement:

Richard

 

[gordmac]

Checking cam timing isn't difficult, you need a protractor for the crank pulley but they are cheap.
http://www.burtonpower.com/tuning-guides/tuning-guide-pages/camshaft-fitting-timing.html

 

[Jokani]

Here is an update on where I am.

I removed the injector but could only get a thin piece of wire down the injector hole, so thin, that it was impossible to accurately determine the cylider position.

Putting a thumb over the injector hole (cylinder 1) I could feel the start of the compression srtoke, both valves were shut at this point. It also looked as though the fuel was being injected at the right time. I think I can be confident that the timing is not completely out

Glowplugs removed from cyl 2, & 3, both glow red hot. Cyl 1 not removed and tested as that requires the fuel injector assembly to be removed.

Whilst cranking I recorded the crank pulley rpm, it was only 220rpm, where as it should be 300rpm, but I would think 220 is fast enough to start.

Cranked to see if it would fire, it wouldn't.

Tried lots of times , leaving the glowplugs on for an extended period, warming the block. throttle in different positions etc, even resorted again to easy start.

At at one point it appeared that cylinder 2 may have fired, but if so just the once.

At some point in the process , clyinder 3 re-gained its compression, but cly 1 & 3 haven't.

Any ideas as to what is going on?

I am at the point where my only option is have Gemini lifted out, remove the engine, and send to a yard with a mechanic.

 

[RichardS]

It's really strange. If the camshaft timing with respect to the crankshaft is correct what else could affect compression? Worn rings, too tight valve/tappet clearances, sticking valves, worn valve seats, blown head gasket ..... I can't think of anything else.

I assume that the rings, head gasket and valve seats are OK as why wouldn't they be.

Have you turned over the engine with the rocker/valve cover off. Does everything go up and down and in and out smoothly. Are the clearances correct and are you measuring them at the correct rocker/cam position?

Just a few ideas.

Richard

 

[anoccasionalyachtsman]

I'm afraid that I still think that it's the cam timing. If you can't get tdc through the injector holes then I think I'd have the head off.

btw. Did you see my note in post 26?

 

[VicS]

I'm afraid that I still think that it's the cam timing. If you can't get tdc through the injector holes then I think I'd have the head off.

btw. Did you see my note in post 26?

The OP says he has checked that the timing marks line up correctly. He has even taken the cover off and double checked,
If the marks line up the cam shaft timing must be correct. There is no scope for it to anything else. unless the OP has removed and somehow incorrectly re-fitted one of the gears

Your note in #26 makes no sense.
If you turn the crankshaft 1 revolution you just get it back to the same position. If you turn the camshaft though 1/2 a revolution its mark wont line up with the mark on the intermediate gear

Timing marks:

 

[Jcorstorphine]

Quote from GC post "Here is an update on where I am. I removed the injector but could only get a thin piece of wire down the injector hole, so thin, that it was impossible to accurately determine the cylinder position."

JC : I did think you would have a problem getting a probe down the injector hole as the drawing of the head in the Perkins 100 manual shows that the Glow Plug blocks line of sight and there may be another small obstruction in the combustion space. Have you tried using a probe to establish TDC on either No 2 or No 3 cylinder with the glow plug removed. See page 8 of this manual.

http://fermer.ru/files/v2/forum/132049/perkins100workshop.pdf

If you can find a TDC for either 2 or 3 then you can establish when No 1 is at TDC as the cranks are 120 degrees rotation. According to the manual, the firing order is 1 2 3 so if you have got No 3 at TDC, No 1 will be at TDC with the engine turned 120 degrees. However if there is a timing issue (which if the timing marks line up would seem not to be the case) then you need to work out when the valves are rocking (inlet and exhaust both open

NOTE> I AM NOT SURE IF ABOVE SEQUENCE IS CORRECT AS I HAVE TRIED TO MAP OUT SEQUENCE OF 3 POT ENGINE AND GOT CONFUSED. ALSO A BIT WORRIED ABOUT FIRING ORDER. MANUAL SAY 1 2 3 BUT WONDER IF IT IS 1 3 2

Quote from GC post "I am at the point where my only option is have Gemini lifted out, remove the engine, and send to a yard with a mechanic."

JC: I think this is going to treble your costs of sorting the problem. Why not try and find a Mobile Perkins Mechanic (You don't need to go to an over priced Volvo dealer) You could try Diperk

http://www.diperk.co.uk/

The 100 series engines are used in Gennys, Pumps, Agricultural and Turf Cutting units so I am sure you can find a mobile mechanic.

 

[anoccasionalyachtsman]

The OP says he has checked that the timing marks line up correctly. He has even taken the cover off and double checked,
If the marks line up the cam shaft timing must be correct.

Your note in #26 makes no sense.
If you turn the crankshaft 1 revolution you just get it back to the same position. If you turn the camshaft though 1/2 a revolution its mark wont line up with the mark on the intermediate gear

In post 10 the OP says that there are no timing marks.

And my note in post 28 is with reference to his comment, also in post 10, that if the cam timing is out by 180 degrees he would turn the cam one revolution to correct it. That wouldn't work.

 

[VicS]

In post 10 the OP says that there are no timing marks.

.

The OP refers to the timing marks several times and says he has checked and re-checked them. He is 100% sure that they are aligned correctly!

What he says in # 10 is that he does not believe there are any TDC marks!

 

[Jcorstorphine]

Think there is confusion about gear timing marks and TDC timing marks, read on

FROM OP POST #1.

Removed timing gear cover

Removed intermediate gear - when replaced ensured timing markings were correct, and to be 100% sure I removed the timing gear casing again and had another someone else verify they were correct

Injection pump removed and replaced

OBSERVATION: From the above there are timing marks on the gears


FROM OP POST #10

I do not believe that there are any TDC marks

OBSERVATION There are no TDC marks anywhere that the OP can see but there are Timing Marks on the gears (see above)

FROM OP POST #11

Unsure if this helps, I have been looking through photos of the parts in question, on the timing gear casing, there is this 'TOP' mark, but I can't see that this mark aligns with a mark on the crankshaft pulley, but it must server a purpose?

OBSERVATION It is not Clear if this is a TDC mark but if OP can ascertain when a Piston is at TDC by means of a probe with glow plugs removed, this may help.

I have tried to map out the sequence of a 3 pot engine running a 123 firing order so that I can state without doubt which piston follows a given piston at TDC with the engine turned through 120 degrees but at 01:00 in the morning, my 72 year old brain which is used to 2 pot and 4 pot engines over the last 60 years is totally confused.

 

[Jcorstorphine]

Vic, you should be in bed.

 

[VicS]

Vic, you should be in bed.

Sorry !

 

[RichardS]

Think there is confusion about gear timing marks and TDC timing marks ....

You can say that again!

Richard

 

[Heckler]

Here is an update on where I am.

I removed the injector but could only get a thin piece of wire down the injector hole, so thin, that it was impossible to accurately determine the cylider position.

Putting a thumb over the injector hole (cylinder 1) I could feel the start of the compression srtoke, both valves were shut at this point. It also looked as though the fuel was being injected at the right time. I think I can be confident that the timing is not completely out

Glowplugs removed from cyl 2, & 3, both glow red hot. Cyl 1 not removed and tested as that requires the fuel injector assembly to be removed.

Whilst cranking I recorded the crank pulley rpm, it was only 220rpm, where as it should be 300rpm, but I would think 220 is fast enough to start.

Cranked to see if it would fire, it wouldn't.

Tried lots of times , leaving the glowplugs on for an extended period, warming the block. throttle in different positions etc, even resorted again to easy start.

At at one point it appeared that cylinder 2 may have fired, but if so just the once.

At some point in the process , clyinder 3 re-gained its compression, but cly 1 & 3 haven't.

Any ideas as to what is going on?

I am at the point where my only option is have Gemini lifted out, remove the engine, and send to a yard with a mechanic.

From what you have said I am confident the timing is correct. At a compression ratio of 23 ish to 1 it will be quite hard to turn over by hand. If it isn't then compression is the problem, but why? Thinking on, did you take the camshaft out? If so did you replace the cambuckets etc in the same places? Did you reset the tappets?
Stu