Bongo Fury

Oh the ups and downs of Bongo ownership:
1.Sunday at Lymington

2. Monday getting home!

What hapened? Well van was driving perfectly as I slowed to take a left hand turn, then as i accelerated after the turn..awful noise like the exhaust had dropped off or there was a gunfight going on in my cylinder head! It seems that it's only running on 3 cylinders and the recovery guy reckons it's either a dropped valve, faulty injector or that the cam belt has slipped a notch or too. Does this sound about right?

I plan to check the cam belt 1st, then if thats ok, check the injectors. My RAC man neighbour has suggested that I loosen the nut on each injector in turn with engine running to determine which one, if any, is faulty. If engine runs worse when loosening an injector, then that ones ok, but if engine stays the same, then thats the faulty cylinder. I can then swap the injectors around to determine if it is the injector or something within.

If it turns out the injectors and cam belt are ok, then the rocker cover is coming off to check the cambelt and all the gubbins in there...I should be able to see if there's a valve problem from there. If it looks like there is it's a head off job of course.

My question is .....does this seem like a sensible diagnosis route to take, or does anyone have any other suggestions for possible causes of one cylinder not firing....or ideas for a quicker easier diagnosis route?

If I have dropped a valve, what are the chances of pistonor bore damage etc?

I replaced the cylinder head last year, and the only bit I wasn't confident aboutr doing was fitting the valves in the new head, so I paid a cylinder head specialist to do that....consequently I'll be a bit unhappy if it is a valve!

I assume that if the head comes off I have to replace the head gesket and bolts too, even if they have only been running 8 months/ 15K miles?

Any advice/suggestions gratefully received............Rob

Way out of my depth here dude, but my instinct would be to throw i nthe towel and let a pro look at it. Presume it had a new cambelt not long ago? Dont like the idea of running the engine at all. Its as though it should be turned by hand an a noise listened for. You could do that with the old motors.

Commiserations, good luck & keep us posted.

Mike

Personally I would have thought the cambelt slipping a long shot unless for some reason the tensioner wasn't put back correctly or wasn't replaced whem you had the head off previously. The injector sounds a reasonable possibility and easy enough to check but it doesn't account for the noises you were getting. Valve sounds more like it but I do hope I'm wrong. Piston and other damage - jeez I hope not but you won't know until the head comes off.

I've had engines do weird things when an injector fails, not on a bongo I hasten to add, But 4 cylinder Japanese diesels none the less. The recovery guy is right in what he says by slackening each injector in turn. You will notice a change in the engine note on the good cylinders but should notice no change in the engine note on the faulty cylinder. I would be surprised if it's the cambelt if only 1 cylinder is affected. I would say that it is either an injector or a dropped valve.
If you can determine that it is not an injector or cambelt issue and do remove the head then it is imperative that you fit a new head gasket and bolts without question.
You would be surprised how serious things can seem from a failed injector. Keeping fingers crossed!

Sorry but a valve dropping sounds like a machine gun going off - an injector doesn't. If the noise was a really rapid/loud tapping then the valve is the most likely. This seems more likely because you had someone professionally instal the valves fairly recently. If it is a valve the best you can hope for is a new piston but normally it is a new cylinder head as well and sometimes the block. I wouldn't be keen on turning the engine over at all. The best test would be a compression check. If youve got zero compression on one pot you have lost a valve.

Good luck and I hope it's an injector but I would try compression first.

if you paid a specialist to do the valves then wont you be under warranty for the work they carried out ?

If you remove the rocker cover, you'll soon see if it's a dropped valve - probably have a broken rocker arm, or a huge gap between it and the valve stem. I had one many years ago and got away with just a new valve, but check the piston crown for damage - mine only went when trying to start the engine, so the piston only had a very small mark.

Removing the cam cover is the best way to go without further damaging your engine. If it is a valve it will have either lost a collet (there may only have been one fitted - it can run for ages like that) or the head may have sheared. The former is most likely.

Thanks guys, I do suspect it's a valve so I'm going to take your advice and take the rocker cover off 1st and have a butchers. I was going to do it tonight but a 3.5 hr journey from E. London to Milton Keynes (6 5miles)took away my motivation! Just when you need an auto with aircon!

I'll report back when I get somewhere.

Rob

We are all thinking of you and your bongo at this differcult time.

Best of luck!

Progress report 1!

Well it's not a simple problem to identify! I've taken the rocker cover off, and everything looks ok in there; the springs, arms and collets are all intact, the valves appear to be moving correctly, and the cam shaft is not excessively worn. The tappets seem very loose but the noise isn't tappet noise although I will check/adjust the clearances tomorrow. Oil flow is fine.

Next step taken was to run the engine and slacken each injector in turn. There was a noticeable change in engine sound when each one was slackened which leads me to believe there is compression in each cylinder. While I was loosening no. 4, I couldn't see very well because of all the egr gubbins and didn't realise the whole injector + fuel pipe was moving and consequently I've fractured the return pipe (the curly pipe which runs between each injector).....bugger!

One odd thing is, that when running the engine at tickover, it seems smoother than it did when it broke down on Monday night......the recovery guy + an RAC guy + me all thought that it was only running on 3 cylinders as it was really loud and shaky! Now it seems to be running on 4 although there is a very definite loud internal knocking (not like machine gun fire though smartmonkey!) which seems to be coming from the cylinder head in the region of no. 1 or 2 cylinder.

Tomorrow I'm going to ensure the timing marks are aligned to ensure that the belt hasn't slipped a notch, and adjust the tappets just because they need adjusting!

Beyond that I don't really know what I can do to identify the problem; my RAC neighbour mentioned the dreaded words.....'maybe the problem's lower down' before he left!

Any ideas guys?

Thanks for your input so far......................Rob

Why not drain the oil into a clean container, allow to settle for an hour or two and then decant so you can look at the dregs. Any white metal will be from a crank bearing. If a big end has gone it will lower the compression and hence misfire. The piston will also hit the cylinder head because of the bearing clearance.

Is it just possible that excessive tappet clearance is causing the valve openeing sequence to be 'off', causing a misfire? Not much of a contribution but its all I can offer.

Reading you post, I feel very slightly more optimistic for you. Incidentally, at what point did you pluck up the courage to test the engine by starting it

Good luck - we're rooting for you

Mike

Draining the oil out and inspecting it sounds like a good advice. You are describing little or big end failure noises. When you drain the oil I would take the sump off and have a good look and feel of the crank. You may even be able to check the gudgeon wear if you can look/poke that far up. If you can borrow a diesel compression tester and an oil pressure gauge you will get more info but I would pop the sump off first.

smartmonkey wrote:Draining the oil out and inspecting it sounds like a good advice. You are describing little or big end failure noises. When you drain the oil I would take the sump off and have a good look and feel of the crank. You may even be able to check the gudgeon wear if you can look/poke that far up. If you can borrow a diesel compression tester and an oil pressure gauge you will get more info but I would pop the sump off first.

Little or big end noises tend to be progressive, not sudden like in this instance. My first choice would be rocker cover off, turn the engine by hand and watch the valves though a dropped valve can be difficult to spot. Second would be a compression test.