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thump on starting and judder related ?

9.5K views 32 replies 14 participants last post by  gm6vxb  
#1 ·
Did not want to start a new thread, but I am certain the two issues of the thump underneath the new Ducato when starting up, and the reversing judder problems are related.
The thump I think is associated with engine mountings loading when the engine first fires causing the the engine/ transmission to jump and transmit the noise into the cab/chassis.
If this is correct then the engine mounts could also be the cause of reversing judder.
Whether it is the location of the mounts or the materials used I am not sure, but tempted to make up a solid mount for what I would call the torsion tube between the bottom of the engine and subframe to see if this effects a partial cure.
Have ruled out gear ratios and vehicle weight (but not completely) as the problems also occur on the Ducato maxi van though to a lesser reported extent.
Driving technique may mask the reversing issue but not the thump, so if you have one it should be easy to find a slope to reverse up to see if you have the other. I can get the reversing problem by deliberately adding revs and slipping the clutch. Not the normal way I reverse though so the problem was masked somewhat.
Anyone any thoughts on the above, several people have smoked clutches and damaged gearboxes so could get expensive out of warranty.

Other threads on both problems here and other forums so 'moderators' please move if you think it fits better elsewhere.
Martin
 
#2 ·
Hi Martin

The 'thump' was reported a while ago, and was discussed / reported on the main "Water Ingress" thread :: here ::

I only mention it for further information, not as an admonishment for starting a new thread :wink:

When you were talking about engine mounts the other day, I did wonder about the thump, and whether they were related. One point - in recent weeks, I've noticed that the thump is more pronounced when starting a warm engine, rather than a cold one. This may be to do with a warm engine starting quicker, so the ignition kicks the engine from its rest position. When the engine's cold, it cranks for a second or so, which may move the engine on its mounts, so when it fires, the engine is already in its 'moved' position.

All this reminds me of Minis in the olden days, where you had to replace the rubber bushes in the engine steady every so often to stop the engine rocking on gear changes, and splitting the exhaust pipe.

Gerald
 
#4 ·
Hi Gerald

I remember the Mini engine mounts well, I had a 1964 Mini Cooper great car had more fun in that than any other car before or since(not including Motorhomes)

Just a thought on the warm engine scenario you mentioned, could be the heat has softened the rubber mountings.

Best regards
Broom
 
#6 ·
Hi Martin when I took my van in for 1st service I asked if they had heard of the THUD problem they hadn't but the mechanic called another over and they spent a time investigating must say I got a bit worried when I saw a 6ft. crowbar going underneath the outcome was they could definitely FEEL a type of thump but could not id. anything from underneath they were thinking as nothing obvious was hitting underside it was perhaps the starter causing some some of vibration on engaging/disengaging. So perhaps not a lot wiser but at least I feel happier that nothing is going to come thro. the floorpan.
It may be useful when people take their van in to ask for the THUD to be investigated and post here their garages opinions as it may lead to a common denominator.

Alex.
 
#8 ·
Same as raindancer, the thump sometimes(not always) during cold start. The severity of the thump varies but does not give me to thinking something serious is wrong. I have no problem with clutch judder. I have found no revs are necessary when going forward or backward up inclines.
viator
 
#10 ·
Telbell see it on there. have E-mailed Andy on the judder issue.
Tried by hand rocking the engine backward and forward using either the lifting eye on the left side of the engine, or any other convenient place, then tried pushing side to side.
Was trying to do the same while watching movement on the bottom mount but it started raining.
The first test showed there is more movement compared to my Citroen Berlingo 1.9D.
Not definative but softer mounts on the Ducato and the M/H is much quieter than the Berlingo.

Will be doing more checks and tests this weekend.
Martin.
 
#11 ·
Martin

Good posts.

Like others my 3.0litre only occasionally has what might be described as the 'thump'. Mostly it is a smooth start and now that I do not give it throttle when reversing, until clutch is fully home, it is very smooth. I have not had need to reverse up any steep inclines so do not know if that would change things.

The engine mounts would be the liklely suspects in that Fiat may have traded off a softer mount for smooth quiet running against a bit of flex on start up and reverse.

Ed
 
#13 ·
Just to keep you updated, the weather has been pretty poor for crawling under the van windy, wet and bl***y cold, plus a dose of 'man flu' means I am not really in the mood anyway.
But on Friday I will be taking the van in for some recall work and a first service to be done. Garage is very friendly and have agreed to let me get underneath in the dry to check out the amount of movement on the mounts at start-up (thump) and also to have someone watch the engine while I deliberately get the judders (not the man flu ones).
The garage owner did mention that there is a known issue with the judder problem but would not elaborate.
Before you ask why a first service, the vehicle was built in January 2007 so is technically a year old, so prefer to have known good oil in before the start of a hard touring season.
Martin.
 
#16 ·
Quite an enjoyable morning spent at my local dealers. Had all the required recalls done, waiting for the engine cover which had not arrived but will fit this myself. No scuttle replacement as I had done too good a job myself. Also had oil and filter changed, Van first registered in the UK 10/2007, but was built in 01/2007 so oil was already a year old, at least I know it has been done at the right time period.
Also has a thrash round in a 500, good fun but not the same as the Nuevo 500, too refined, loved the old crash gearbox and burst proof engine on the original 500.
Had a crawl underneath while the van was on a couple of jacks. Van was started while I was underneath and the whole lot twists noticably as it first fires. Looks like the thump on start is just caused by the sudden movement of the engine on the mountings. Definately nothing is hitting the underside or inside of the engine compartment. Did however find a loose wiring harness just above the exhaust which could have caused problems in the future.
We then did a reverse test with the bonnet open and me hanging onto the front of the van. The whole engine rocks quite a bit even under mild judder. Could not get a good look at the bottom mount under the same conditions, not safe lying under the wheels while the van was reversing toward me, but this is my main suspect now as maybe allowing too much rocking motion.
Thinking about it, if you go forward you either get judder or the tyres spin releasing some of the torque, in reverse there is more effective weight over the wheels so the tyres cannot spin as easily. The torque has to go somewhere so the engine and transmission will rock violently until either the clutch slips a little, or the driver lets the clutch slip to relieve the judder.
Result is either you burn out the clutch or (like a hammer drill) you break something in the transmission chain.
Lowering the reverse gear ratios (as has been suggested) will only mean that more torque can be applied, engine can still rock, same problem.
I took some measurements of the bottom mounting and when I get time will make up a solid version to see if it makes any difference. I know it will make the van very noisy.
BTW it appears that the recall 5209 for the 160 gearbox bearing might also be happening on the other six speed gearboxes (2.2/2.3L) as well.
The garage will speak to FIAT about this problem, but as I was told they already know about it and could/ may be looking for a cure.

So has anyone out there looked at this problem from a cause and cure perspective with a more mechanical background than me. What conclusions do you come to.
Martin.
 
#17 ·
So has anyone out there looked at this problem from a cause and cure perspective with a more mechanical background than me.
Martin-is that possible? :wink:

Many thanks-the thought of a reversing test with the bonnet open and you hanging on the front? The mind boggles!

But Fiat say it's a characteristic of the vehicle! :roll:
Will you be posting your findings on OandA??
 
#18 ·
Telbell hi, there seem to be lots of trades on here with loads of experience, I would have thought there would be at least one with a mechanical or vehicular engineering background. I could probably sit down and read up on engine mountings, Google just gave me 2.3 Million hits on the subject, but I think I would be an old man before I came up with an answer.
Just above where the spotlights are fitted on the front bumper are two big slots, my size 12's fit a treat into them, you have to trust the driver though and we were in their yard so no chance of prosecution!!
Not going to post on O&A. Maybe I misinterpreted the E-mail but Andy basically said unless I read everything on there I did not fully understand the problem and I should go and try reversing up a hill to see what happened. Also a few other points I will not go into on here.

Yes you are correct with what FIAT say, it is a characteristic, they nearly all do it
:? even if they shouldn't. Having said that I reversed up the same slope we were testing on with no judder. Different technique to the mechanic tested with.
Martin.
 
#20 ·
Basically, handbrake on, put into reverse gear, start to let out clutch until engine revs start to drop, release handbrake and simultaniously let out clutch gently. Engine management will then try to keep revs at tickover speed, at which time you can apply more revs if you want to. You do get vibration but not judder, see short write up off internet below.

Googling 'engine mounts' found the following link and info, only up to 70 of 2.3 million

http://www.ingentaconnect.com/content/ind/ijvd/2004/00000024/00000004/art00001 :?
There are many different kinds of mounts, among which are the engine mount and the transmission mount. An engine mount attached the engine to the chassis. A transmission mount, on the other hand, work with engine mounts to control torque and minimize the vibration transferred to the chassis. It is also the trans mount which keeps linkages in their proper positions. They form the rear support of the transmission assembly as well as the right angling of the front of the driveshaft.

Martin.
 
#22 ·
Bottom mount tests

Made up a solid bottom engine mount yesterday as it was a wet day (what wind).
Made it out of a couple of three point links off a tractor cut down and welded, washers to pack out the mount to fit the sub frame and engine mounting locations.
Fitted it and did a few reversing tests. Able to get mild judder but now only under real extremes trying really hard up a very steep slope on a loose surface. Top engine mounts are probably contributing now.
Vibration transmitted to the chassis is very bad, but knew this would be the case. Did not want to do too many tests as there is a real possibility of doing damage to the sub frame mounting.

Problem now is to find someone with more experience of resilient engine mountings.
Another thought is to fit a torsion bar to somewhere near the top of the engine. Again need more expert help.

Martin.
 
#23 ·
Martin

Problem now is to find someone with more experience of resilient engine mountings.
Sounds like you're half way there then? Ever thought of renting out your skills to Fiat?? (not entirely tongue in cheek)

If you have no joy on MHF, OAL may well have people who could help?- "Combined Skills" and all that.

Keep up the good work!
 
#24 ·
Re: Bottom mount tests

gm6vxb said:
Another thought is to fit a torsion bar to somewhere near the top of the engine. Again need more expert help.
Martin.
I'm not it I fear - the expert help that is! :wink:

Would a heavy duty (double acting) gas strut or an ordinary suspension shock absorber do any good if attached to the top of the engine?

That might damp things down without putting too much stress on either mounting point.

Just a thought! :D
 
#25 ·
Just to finish off the thread, I am certain now that anyone who has judder will also have the startup thump.
I have now done some modifications which include replacng the bushes in the bottom mount and fitting a torque rod with bushes to the top of the engine.
Managed to get a bottom mount from a breakers yard so then went to a local company and asked for bushes firmer than those fitted. These cost ÂŁ20 each (one each end of the bottom mount).
I then had fabricated a rod with bush mountings on each end and had bushes (ÂŁ10 each) fitted by the same company.
Existing bolts on the bulkhead were used, and a fabricated bracket fitted to the head on the gearbox end of the block. This was the trickiest bit as there are a lot of pipes and things in the way.
Initial testing shows an increase in engine noise transmitted to the cab area, and a couple of harmonics at 1500 and 3000RPM, not bad but noticably louder.
No thump on starting now, this I am sure has been cured by the bottom mount bushes, no judder even when I try hard to make it happen. I am slightly concerned though that it may be possible to break something in the transmission chain if I dropped the clutch, all the torque is now having to go to the wheels and not being allowed to wobble the engine, so no warning of any overloading.
I will be going away next week for a longer test, fully loaded and into the hillier parts of Scotland but results so far look good.

We will see how long it takes for an 'official' modification to come out, if it is better than mine then I can change back the mountings very quickly and ask for it to be done.
This mod works on a Lunar H601, it probably would not work on other vans as some have no judder (not worth modding then) and others have severe judder (mod may not tame this).
Martin.
 
#26 ·
Martin
Congratulations on all your work- but I wish I could understand it all :roll: :lol:

So in a nutshell- and for a nontechie like me, what's the bottom line? The thump and reverse judder are due to......?
and are you able to say what a likely Fiat fix may be?

Is it worth you telling Fiat what you've done? Now or after your extended trip?