volvo penta 2001

[Gaz22]

Can anyone with a VP 2001 engine comment on back pressure from the engine, this one has just had a top overhaul reground valves etc, the rocker box and joint are aligined correctly to allow the engine to breathe normally but it now seems to have more back pressure than before.

Can anyone comment on this or tell me how to somehow measure the back pressure /forums/images/graemlins/confused.gif

 

[VicS]

Not quite sure what you mean by back pressure.

From the exhaust system due to restriction to the flow which can be caused by collapsing hose or choked up water injection elbow.

Or do you mean a build up of crankcase pressure due to wear of piston rings and/or cylinder bore and/or restricted crankcase breathing due to incorrectly fitted top cover gasket.

 

[Gaz22]

Yes, crankcase pressure now seems to be exessive through the dip stick or the oil filler cap,

The head was recently removed for the valves to be reground, the engineer who did the job said the piston bore was ok, the engine starts and runs ok and the top cover and joint is aligined ok

have been told to run the engine at 90% in gear for a couple of hours to let the engine run its self in again, not sure about this seems a bit drastic.

cheers for any help or suggestions

 

[Bilgediver]

Volvo engines usually manage the crankcase pressure by breathing to the intake on these small engines. SOmetimes this is an external hose to the aircleaner however they have also utilized a system of direct breathing from the pushrod space to the inlet bore above the inlet valve.

If your engine has the latter then maybe the breathing valve is partially blocked or stuck....Vic is a dab hand for finding manuals....maybe we can check this however it might require the head to be removed /forums/images/graemlins/frown.gif

These systems can cope with quite worn engines so seems in your case it just isn't doing its job.

 

[aluijten]

A common thing to go wrong with these engines is that the gasket between the cam-shaft (actually rocker box) cover and the cylinder head is mounted in mirrored way. There is a small breather hole that leads the crankcase pressure to the inlet, this hole can be blocked if the gasket is mounted wrong side up.

Cheers,

Arno

 

[VicS]

There is a small breather hole that leads the crankcase pressure to the inlet, this hole can be blocked if the gasket is mounted wrong side up.

That is what I was referring to when I said "restricted crankcase breathing due to incorrectly fitted top cover gasket"
I did not want to labour the point as Gaz22 seemed to be saying that he knew it was correctly fitted. It is mentioned in the Workshop manual Paragraph 21 in the "assembly" chapter. It is something that should be rechecked I think,

I don't understand the suggestion that it should be run at high speed for a period. After a re-bore one would normally follow a running in procedure of gentle running for a period.

Even if the bores are OK it could still be problem with a piston or rings, but let's not go there just yet.

 

[Gaz22]

cheers the top cover gasket is fitted correctly and the hole is clear inside the top cover

Would need to find more info on the hole in the head with the breather valve as bilgediver said.

if the older style engines had a pipe to the air cleaner where did it suck from (a fitting on the top cover??) this may be an option to let me use the boat this summer and remove the cylinder head this winter if the breather valve is blocked.

 

[VicS]

The earlier ones that I know about had a hose from the oil filler cap to the air intake "frying pan" hose 31 in This diagram of an MD11C for example

 

[Bilgediver]

There is a small breather hole that leads the crankcase pressure to the inlet, this hole can be blocked if the gasket is mounted wrong side up.
**************************************************

I think this may be referring to the cylinder head gasket....Bells are ringing /forums/images/graemlins/smile.gif

I modified an older MD 2 by replacing a blank flange on the upper crankcase with one fitted with a 1/2 " pipe stub which was connected by hose to the air inlet.

Maybe you have a convenient blank as otherwise you might have to get your fella to remove the head and fit a new head gasket the right way round .. /forums/images/graemlins/frown.gif

 

[VicS]

get your fella to remove the head and fit a new head gasket the right way round ..

Surely this is not a problem with the head gasket. Won't the crankcase breathe up to the valve cover via the whacking great space where the push rods come through. You cant block that off with the head gasket!

This diagram may not show the push rods but they come though the opening nearest to you in the gasket.

 

[Gaz22]

When the guy fitted the cylinder head gasket he pointed to me that the gasket was stamped with top indented to it and could only be fitted one way so fingers crossed thats all ok

VicS would you have a drawing of the breather valve to try and let me get my head around all this info, these parts drawings you have are a good source of info where can l buy them

looking at your drawing of the MD 2 our oil filler cap may not be the best option my Dad says he will drill a 10 mm hole through the top cover and fit a 10mm bolt with a 3 mm hole through the lenth of the bolt then fit a hose over with a jubilee clip and then route it to the air cleaner any comments on this welcome

thanks for all the comments been a great help /forums/images/graemlins/smile.gif

 

[VicS]

these parts drawings you have are a good source of info where can l buy them

The Schematics are here

A breather could be fitted from the top cover but you must give some thought to it. If a lot of oil mist its carried over then the engine could run uncontrollably on the oil. Careful positioning may be good enough to stop it, a baffle may be necessary or some other form of trap.

There is a cause of this problem that ought o be found. I am quite certain that it can't be anything to do with the head gasket being fitted incorrectly and you are sure the top cover gasket is fitted correctly. If it starts easily runs well it is unlikely to be piston rings . My money would still be on that internal breathing system being obstructed somehow.

 

[Gaz22]

Cheers Vics for the schematics have had a quick look at them still not found the breather valve yet but will do with time.

will keep you posted on how this transpires, thanks for the drawings and comments.


From the only Kingdom

 

[simon1964]

Hello Gaz

I have recently bought a boat with a volvo penta 2001 engine that seems to be showing the same symptoms as your engine, some kind of crank pressure build up ( i think) causing it to push the oil out through a seal somewhere. I am planning on bench running the engine to locate exactly where it is coming from. I was wondering whether you solved your engines problem and if so how? i realise that this thread ended a long time ago but if thought it was worth giving it a shot

Cheers Simon

 

[Seatrout]

Hi Simon,

Same problem on my VP2001.... any news re breather routing ?

Roger

 

[simon1964]

Hi there Roger,

Can you tell me a bit more about your problem. Is it losing oil from the front or back of engine, Is your engine running ok and does it start ok?

Cheers Simon

 

[Seatrout]

It was a recon engine sourced from south of england.
Starts fine had only light usage last season but some prolonged runs this season. Oil coming out of dipstick tube under pressure.... runs fine.

R

 

[simon1964]

Hi roger,

I,m not what you would call an engineer. But it does sounds like crank pressure is causing your problem, which was not the problem with my engine. i had oil coming from the front and rear crankshaft seals. but no oil coming from oil dipstick tube. i replaced the crank oil seals and this solved the problem on my engine. being as i had to remove the engine to get a the seals i ended up stripping down the engine and doing a rebuild which included new piston rings. Whilst it was stripped down i had a look at the breather journals which is a strait 3mm hole from crankase to rocker cover. i think if it was to get blocked by something it would be easy to poke some wire down there to free up any blockages (If it is blocked by any gunk i would be worried as there may be other blockages in other oil journals causing more serious problems). So i would recommend you check that the breather is not blocked or that the rocker cover gasket has been fitted correctly. if all this appears to be ok i would then try to get a compression test to see if thats is normal, if it appears to be on the low side i would investigate the piston rings. I hope this might be of help to you.

 

[Seatrout]

Hi Simon,

Thanks for your advice. The boat is at Oban at the moment where I've been the last two days doing my amateur mechanic on it.
The head was taken off and I found some carbon deposits under the gasket between cylinder and oil channels (so a possible cause).

The good thing about this exercise was being able to cure the slight overheating problem by the introduction of hydrochloric acid to the cooling galleries of both block and head to loosen and chip out some deposits. With advice from another forum thread, I also expanded the little holes in the water feeder pipe through the head with a 6mm drill.

This strip down gave easy access to the sail drive and I found that the oil was rather emulsified, so a pump out and replacement with new oil will hopefully see me to the end of the season.

Thank you goes to Roddy of Roddy's garage in Oban who gave me a welding rod for a couple of quid into the charity bottle. I needed one of these to clean out a wee breather channel which goes through the head and into the air intake (the one which would get blocked if the rocker gasket were on upside-down).

Having put it all together again, unlike other previous mechanical adventures I was amazed to find no bolts, nuts or screws lying in the tray! Further amazement came when it actually started and ran as smooth as a sewing machine and passed the trials I put it through. There still appears to be positive pressure up the dipstick pipe, but not enough to pop the dipstick.... to be super sure, an additional new rubber seal ring was applied to the d/stick handle.

An engine removal and strip down to look at the p/rings is in the diary for end of season.

 

[steadyeddy]

Is it possible the fitter removed the carbon ring which had built up round the top of the piston bores,or cleaned the tops of the pistons without leaving a ring of carbon round the edge of the piston,just a thought.