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View Full Version : Engine shake between idle and 1600rpm


Yom
17-01-2008, 10:44 PM
Hi Folks,

Well, bear with me here. After the saga (which I blew way out proportion) with my injector pump change, the patrol is back and driving quite well. Not nearly as much power as it had before all this, but its blowing alot less smoke so the fueling must have been turned up a bit on the old one.

So while I'm happy (actually no, ecstatic) to be able to drive it around at the moment and not hold up sloths, I'm still a bit worried about two things and as I'm sure the poor mechanics are well and truely sick of seeing me (i know i would be) I would like to see if theres a chance anyone has experienced something similar so I could at least figure out if I need to pick up the phone again or not. :(

Basically between idle (which now seems to be around 850 to 900rpm which seems a little higher than standard, but i like it so im not whinging) there's a strange, almost harmonic, vibration through the vehicle. CLutch in or out, doesnt matter. It was there after the new injectors were put in - when the idle was down at 650rpm and it was quite noticeable in that it felt like an old truck rather than the fairly smooth engine it was beforehand. It sort of goes away between 900rpm and 1200rpm but then comes back between that point and around 1600rpm. After this point, it runs rather nice and smooth.

Its only noticeable when the engine is under no load. What worries me is that this doesn't sound injector related - an injector problem typically shows all through the rev range?

Now ordinarily I wouldn't fuss too much about this but something else which is different about the old girl is that it is louder. As in the engine itself is physically louder than it used to be - there's alot more tappy noise from the top end.

OIL - CHANGED. No change.

Is it possible the severe knocking it experienced when one of the old injectors "died" has damaged a piston or a valve? It was a bloody nasty knock and saw mabye 3 to 4 seconds of 2300rpm before I backed off realising the noise was coming from the engine, from there I had to give it around 1000rpm to get up a hill and down my driveway which is quite long (any less RPM it just didnt have the power to do it).

Sorry for the long winded post but its best to explain properly I guess.

Tracteur Tom
17-01-2008, 11:36 PM
Could it be a loose baffle in the exhaust ???

Yom
17-01-2008, 11:55 PM
Thats one thing I haven't discounted. The exhaust doesnt rattle or make any nasty noises but I've been a little suspect of it for a while. Been looking around at my options there - keeping an eye out for a second hand 2.5".

nastytroll
18-01-2008, 12:11 AM
sounds like a pump issue, either the rollers are not all equall sizes or it may have a faulty feed pump.
Was the pump reco'ed or just another pump?

Yom
18-01-2008, 09:36 AM
Reco'd.

I'd like to scrap the idea that its the pump. Its been into one of brisbane's best diesel specialist shops twice now - if it was a pump problem they should have picked up on it by now.

Fuel economy so far is excellent. Going by KM traveled and how far the gauge normally moves I'm estimating ~10L/100km.

ITS A FORD NOT A NISSAN
18-01-2008, 08:47 PM
the only things i can think of is
valve clearances slightly out on a couple of cylinders
or the cracking pressures in the injectors are slightly different

im pretty sure mine did something similar before i put the turbo on and wound up the fuel

Tracteur Tom
18-01-2008, 08:55 PM
I was thinking dual mass flywheel, but I recall from your other posts that this is a TD42 ? Are you sure its the engine and not something vibrating on the body / chassis as a result of the engine ? I've had all sorts of strange buzzes on mine caused by loose things eg bumpers, exhaust mountings etc etc - its an age thing ! Also check to make sure the is not a crack in the floor / bulkhead join, this can cause weird vibs or a loose body mount, all the usual stuff.

Tracteur Tom
18-01-2008, 11:24 PM
Yom, I see you've been posting in the GU section on the Miss at idle thread, some ideas there ? I dont think you can discount your new pump and injectors from this problem. Just hope the severe knocks you had didn't crack the pistons, now that would spoil your weekend.

Yom
19-01-2008, 11:03 AM
the only things i can think of is
valve clearances slightly out on a couple of cylinders
or the cracking pressures in the injectors are slightly different

im pretty sure mine did something similar before i put the turbo on and wound up the fuel

Going to buy a new spacer tool thingy and do them asap.

G60 Rock Crawler
19-01-2008, 01:03 PM
Could it be warped fan blades.

I cant see a Harmonic balancer on my ute, but if theres one there and car sits for a while the belts warp the rubber in the balancer?

mav_perth
19-01-2008, 01:22 PM
something else, mine has a "lumpy" idle - gearstick shakes around a little @ idle. It has low compression in front cylinders - due to cylinder glazing I believe. So this makes compression strokes a little uneven & hence lumpy???

Once going smooth as.