knocking noise and feels like running on 3 cylinders

[paul_c]

1991 SWB Pajero 2.5TD manual

Plagued with poor performance (only able to do 65mph on the motorway) I asked the dealer who I bought the car from, for advice. He advised and showed me how to turn up the fuelling. The car didn't smoke hardly at all before, literally there would only be a small puff of smoke at full throttle and low rpm. So I turned it up a little bit. The black smoke at low rpm and full throttle is a little more, but there was no smoke, say, above 1800rpm, even at full throttle. Also the idle speed had jumped from around 850rpm to 1300rpm, so I turned this down by adjusting the stop screw on the fuel pump, where the throttle cable is. I took it on a 10 mile run including some motorway use, and the car is now able to do about 75mph.

2 days later, I went to nip to the shops and there is now suddenly, a knocking noise coming from the engine, and at the same time it feels really rough, as if its running on 3 cylinders. It also feels well down on performance, although the idle speed isn't really affected. If I use full throttle the knocking is worse but the smoke output is unaffected.

Any ideas what it could be? Since the fuelling change was minor, I don't think its related to this and I think its merely chance that the engine is now failed in a more serious way, for example a fuel injector has failed, valve problem or maybe even big ends or something?

I've turned back the fuelling to where it was, and its still the same.

[Onan The Barbarian]

I had a very similar problem with one of my 2.8s, Paul... it developed a loud 'diesel' knock... sounded more like an old Transit van! My mechanic tried to cure it by adjusting the fuel pump but, although it cured the knock, it made it run on three cylinders. It turned out to be one of the injectors was failing... dripping instead of spraying.

Hope that helps.

[paul_c]

Well, I've had a chance to look at it and found the issue.

Taking the rocker cover off


Note, the rocker shaft snapped


Another pic showing the bolt which should have held it down, but which is screwed into thin air


This small piece of metal had broken (off)






I phoned the dealer to tell him and they might be able to supply the parts to fix it.

[Onan The Barbarian]

Yes, I guess that might make it run a little on the rough side!

Best of luck getting it sorted out, Paul... hope the dealer comes through for you!

[john cook]

you may have a problem getting a cam cap to fit. they are line bored so are matched to the head.
number 5 cap has the oilway in it so dont get them mixed up

[bigt]

Im surprised it ran at all. I had a cam belt tensioner bracket break, cam belt jumped throwing out the timing resulting in 4 bearing caps smashed. Due to the caps being line bored I found nobody interested in rebuilding the head. The other option was a new head from Milners. Head came with camshaft and valves. Make sure you use a mitsubishi head gasket and new head bolts

[john cook]

i wouldn't recommend a milners head.

they are cheap Chinese castings and don't seem to last long.

im in the middle of a 4d56 rebuild at the moment myself.
i got a genuine reconditioned head from these guys
http://www.cylinderheads.co.uk/
a genuine gasket is a must and ive just found out my headbolts bottom out so new ones needed

but lets not jump the gun
your posts don't show your location. i have a spare set of cam caps that you could have if they fit.

[paul_c]

I've now stripped it down a little more, to investigate the full extent of the damage. 2 cam caps are affected, No.5 had 2 parts broken off (the 1st part is shown in the pic and the 2nd part was a small sliver of metal, which I have now retrieved from the engine, so it won't be blocking an oil passageway). No.4 had what appears to be a helicoil, which has stripped and this might have been the start of the failure sequence. Thread loosens and strips, vibration rattles around the rocker shaft and it twists and bounces on the cap loosening the bolt, then it snaps and forces are transferred onto No.5 which breaks into 3 parts.

I've obtained replacement cam caps, fitted and torqued them down and it APPEARS that the camshaft freely turns, so maybe I'll get away with it despite them being line bored? Fingers x.

Need to go back tomorrow, to see if the garage has found a suitable rocker shaft for me, otherwise its £65 + VAT from Milner's off road.

Hopefully I can save this engine with the minimum of hassle, don't particularly want to get into having to swap the head over.

[bigt]

[john cook]

they must have changed their suppliers.

not the cheap ones anymore then.

yes the 4d56 lump is fitted to the h100 van.

[paul_c]

Update: The rocker shaft arrived today, so I fitted it but had problems torquing up the bolts which hold it onto No.1 and No.2 cam caps. I used loctite on No.1 and tightened No.2 as best I could. Then put everything back together. Then I started the engine and gradually ran it, it was fine at idle but I gradually increased the revs - then the same symptoms came back - knocking/rattling noises,loss of power and roughness. I had a pretty good idea of what had happened. So I stripped the intercooler and rocker cover off, and took a look - sure enough, the thread had stripped out of No.1 and No.2 cam caps. Luckily, the brand new rocker shaft hadn't snapped too.

So I went back to the garage and they gave me some more caps.

I'd heard that the caps are designed to be interchangeable so I didn't worry about fitting them. Then I put everything back together, very carefully torquing things down and making sure everything was clean too. Then I started it again and it started and idled fine. No noises, no loss of power, all ok. I revved it up a little and it was fine too. Then I gradually increased the revs, and at about 2500-3000 rpm there was an almightly crack and a sound like a skidding noise and the engine stopped. I tried restarting and it spun with no firing.

So I stripped the intercooler and rocker shaft off again, and the cambelt cover. The damage this time is: the cam has come off the cam sprocker, snapping the locating pin and the bolt with it, and also 2x rockers have shattered. I read elsewhere that this is normal, and these are the "sacrificial" part that breaks should the cambelt snap.

So now, the parts definitely needing replacement are:

cam
bolt holding cam sprocket to cam
No.1 cam cap looks dodgy, hairline cracks all over it
an inlet rocker
an exhaust rocker

I now need to decide whether to get just those parts, and replace them, and see what happens; or bite the bullet and replace the entire cylinder head, which will also give me a chance to open up the engine and inspect the tops of the pistons for damage, and it will have all new cam, cam caps, rocker shaft, rockers, valves, etc. The engine had blown its head gasket and had been fixed 2 months earlier or so, by the garage, although I don't know what parts were replaced (eg, head?) or whether the head gasket was merely replaced, but the other components reused.

So I'm looking at a further bill of at least £166.75 (replace broken parts, keep the existing head) or £607.78 for a new head, etc.....

[paul_c]

Here's the pics:

[john cook]

ive spent the last 5 years playing with these engines trying to get more power out of them.

ive discovered its crucial to get the valve clearances right 0.25mm HOT.

if you set them cold the clearances close up causing the valves to just hit the pistons. looks like your problem.
the rockers are designed to be "sacrificial so as to break and save the rest of the engine.

its very rare for the valves and pistons to become bent or badly damaged.

i have a cam and spare caps if you need them. sadly none of the earlier type rockers though

[paul_c]

[paul_c]

Update

I know its been 2 weeks but its taken this amount of time to get anywhere. After a delay, the dealer came up with a new (used) cylinder head but it was off an L200. It is very similar but not the same, the only difference is the valves are flush on the new one, while my valves are protruding type on the old one. I had to swap over pretty much everything except the cam, cam caps, rocker shaft and rockers (one was broken so it was replaced). It had come from an engine with a rod failure. So I swapped over the glowplugs, injectors, coolant flange, sensors, etc

I sent it away for skimming and cleaning up, on return I took apart and lapped in all the valves and each one seated properly and operated smoothly. It was fitted using a new cylinder head gasket and the bolts were carefully cleaned and oiled, and the threads cleaned out, etc. I also took the opportunity to fit all new balance shaft belt, cambelt and tensioners, and drive belts. I've double and triple checked the timing and turned the engine over many times in the process! I've followed the marks as best I can in Haynes, bearing in mind that I'd properly identified the balance belt ones but I'd never had a chance to look at the cam and fuel pump in relation to the crank. I'd taken apart more than necessary (radiator and some of the front end too) so it took about 2 days to do all this and get it all back together today.

Now it turns, but doesn't start! Its a strange kind of noise, sounds like a whirring rather than the usual turning over noise. So I am thinking, possibly, that there's no compression. I took the rocker cover off again and checked the valve clearances (I'd initially set them at 0.25mm cold) - all fine. Then I removed the injectors and spun the engine over briefly - atomised fuel seemed to shoot upwards out of the holes. I poured a little oil down each of the glow plug holes (thinking it would help seal the piston rings, if there were any issues there) but its the same.

I'm wondering if there's anything obvious I can try before spending £60 on a diesel compression tester. For example, would the fuel system (high pressure side, fuel pump to injectors) need priming and if so, how do you do it?

[treeboa]

if your injectors are spraying then the pump does not need bleeding
can you turn the engine over easy by hand, thats a clue that the compression aint there, not got your pump timing 180 out have you

[paul_c]

I've done a bit of searching around and might have found the problem. The crank pulley might be on the wrong way round, so the TDC mark I lined up to, isn't really TDC.... I'll pull it all apart tomorrow and see whats going on.

[Xpajun]

Think I've got to this post a bit late - had similar problems all last year The rocker shaft went first in the early part eventually ended up running on 2 cylinders (yes it will but it doesn't pull very well ) Then towards the end of the year I did a head gasket change and had nothing but problems afterward similar to all your later problems - every time I set the timing it would be ok on idle and then bang a knock a lot when revved. When I checked it I found the timing to be way out again, at one time I found the location pin between the sprocket and the cam shaft sheared. After replacing this the problem still occurred, due to shortage of time I replaced the engine but I suspect a sheared woodruff key on the crankshaft might be the problem.

On the question of tappets the gap on the older engines is 0.25mm but on the later engines that have the rollers in the rockers it is 0.12mm according to the Mitsu manual

[paul_c]

Do you mean rollers on the cam side? If so, then my valve gaps are too wide, but at least its the 'safe' side. I can readjust these with no worries.

I phoned the dealer and he suggested cracking off each injector line with a 17mm spanner, to check if it runs the same or poorer. I loosened the No.1 connection and the rough running went away and the revs dropped. Then all the others, and on each one, the revs dropped and rose again on tightening it. And then the roughness and missing went away. So maybe there was a slight airlock in No.1 injector?

It was still smoking too much, so I turned down the fuelling again. The smoke went away, so I nursed it over to the dealer who had offered to look at it. He says its all okay and is running sweet, so I took it on the motorway for a proper run and it only does 58mph....

So I'm going to redo the valve clearances and turn up the fuelling again.....but its looking better now!

[paul_c]

I've set the valve clearances and also tweaked the fuelling once again. It smokes if I use full throttle under 2000rpm or so, but otherwise its okay. I took it for a run on the motorway and I can now achieve a top speed of around 67-68mph, which was about the performance it was before all the troubles started.

So, for now, I'll say its fixed.

I still need to attend to a few little jobs:

- slight whine - probably a belt overtightened
- slight coolant leak - seal on O ring to replace
- oil & filter change
- refit underbody protection plates

I'll leave the fuelling as-is for now and see how it copes.

[john cook]

you could try this

http://dodgeram.org/tech/dsl/more_power/Power_ve.htm

not for the paj but the adjustments are the same.

it shows how to adjust the pump for different loads.

(but make sure you take note of the original adjustments before you start)

[john cook]

if its running fine at low revs and no power at high revs maybe its not increasing the fuelling as the turbo boosts.
the diaphragm in the top of the pump is prone to failing.

[Pajero90]

Hi Paul C

I have a 1990 Pajero with only 100, 000kms. I have exactly the same problem that your truck had, with the breaks in the same place (both of them)!!

If you had to do it all over again, would you have ordered a built up head, so that you wouldn't have had trouble with the cam caps and fitting the rocker shaft?

I've read these horror stories about not getting the cam caps to fit and having it lead to even more troubles, as in your case.

If I order a new built up head from Milner, there should be nothing to do but bolt down the head properly with a new head gasket, right?

Thanks for any advice.

Tim

[Xpajun]

Wow.... what a thread revival

I know you asked Paul the question but I don't think he's been around since this post

Unless you have a problem with the head don't replace it - it's that simple

get a new rocker shaft to fit - the Milners one is OK

Re: the threads in the top of the cam caps renew the threads by using a heli coil type thread repair kit they are really strong - in fact stronger than the original thread.

Take off each cap separately to renew the thread then replace

[Pajero90]

Thanks for that Xpajun (please see questions in the text 1-2)

When the rocker shaft broke in 2 places it destroyed the last two caps as well.

From my research, the threads on the new caps won't line up with my head that's why I thought I needed to replace the whole head built up.

1 .Are you saying that I should be able to get them to line up using this thread repair kit that you mentioned?

Also, I've heard that, very often, when a new shaft is fitted, the caps won't torque down properly and the shaft can become difficult to turn.

2. Do you think that this is a concern?

Thanks for your help, I'm going to be elated once this truck is running again!

Tim

[Xpajun]

[Pajero90]

[/quote]When you say destroyed, do you mean physically smashed them to pieces or just stripped the thread - pics would help Wink

[Pajero90]

Anyone else want to chime in?

This thread clearly points to a problem with using a new rocker shaft and caps because of the problem of caps not lining up. The original poster had his engine completely destroyed when he tried to install just the shaft and new caps. I've heard from one person that thinks that this is an unusual case and that I should go ahead and install a shaft and new caps instead of a built up head. Does anyone else think this is so?

thanks, still researching, Tim