Fiat 126 Chat => Fiat 126 Mechanical Problem Solving => Topic started by: 5816nick on May 25, 2019, 08:46:05 AM

Title: Terrible Engine Vibration
Post by: 5816nick on May 25, 2019, 08:46:05 AM
Hi Guys, I have a Terrible Vibration on my Aircooled 126 at about 1750 RPM to 2000 RPM, It is seriously  so bad you cannot drive it, I have replaced the Gearbox and Engine Mountings, The new mountings were recently Purchased and the only difference is spring is Longer and there is a Green Plastic Bush - I wasn't sure where this went as The Original set up didn't have one? 

I was reading on here about A Terrible Vibration on BIS Models with the Flywheel Being Put on Incorrectly  - Can it happen on Aircooled Models if the Flywheel has been put on Incorrectly  ?
Title: Re: Terrible Engine Vibration
Post by: Bar Vitelli on May 25, 2019, 10:56:17 AM
I’m not sure if the spring is the cause of the vibration but it sounds like you’ve put an early aircooled spring into a later model which can’t help as they must be shorter for a reason. Upload a video if you can as it might help give some clues as to the cause.
Title: Re: Terrible Engine Vibration
Post by: Gadge on May 25, 2019, 01:06:38 PM
Could be the spigot bush that the gearbox mainshaft inserts into. I’ve had this happen before
Title: Re: Terrible Engine Vibration
Post by: Gordan on May 25, 2019, 08:58:16 PM
Could be the spigot bush that the gearbox mainshaft inserts into. I’ve had this happen before

If I understood this correctly i had the same problem, only mine vibrated only in 1st gear….
Title: Re: Terrible Engine Vibration
Post by: 5816nick on May 25, 2019, 09:11:29 PM
Hi Guys. Mine Vibrates so badly - both when stationary and when driving, between 1700-2200 RPM it is terrible, it is so bad it cannot be driven, I've driven it once round a car park so far....

I've read about flywheels being put on incorrectly on 126 BIS and am wondering  are Aircooled 126's the same in that if you put the flywheel on wrong it will make the Crank out of Balance?


Thanks Nick
Title: Re: Terrible Engine Vibration
Post by: Pete126 on May 25, 2019, 10:00:44 PM
Have you checked for play in the alternator bearings? Try taking off the fan belt for a moment and see if the vibration disappears also check that the fan hasn’t started to do disintegrate, if some of the blades are broken or missing this will unbalance the engine also.
Title: Re: Terrible Engine Vibration
Post by: 5816nick on May 26, 2019, 10:19:01 AM
Thanks Pete, I Didn't think of the Fan or Alternator! I'm working on it on Monday so i'll let you know what i find.

Kind regards Nick
Title: Re: Terrible Engine Vibration
Post by: Minijohn on May 26, 2019, 01:20:29 PM
Is it actually firing on both cylinders?
Title: Re: Terrible Engine Vibration
Post by: 5816nick on May 26, 2019, 01:32:23 PM
Hi, Yes it runs very well on both cylinders, goog compression on both cylinders,  ticks over fine, revs up fine both stationery and when driven but as soon as you hit 1700-2200 RPM -  this terrible vibration, the whole car shakes violently - it's so bad you can't drive it >:(
Title: Re: Terrible Engine Vibration
Post by: 5816nick on May 27, 2019, 08:40:19 PM
I Took the Fan Belt off and Ran the engine for a few seconds, The Vibration is Still there and as bad as ever ..... I'm Stumped
Title: Re: Terrible Engine Vibration
Post by: Bar Vitelli on May 27, 2019, 08:54:59 PM
Does it make the noise when idling?
Title: Re: Terrible Engine Vibration
Post by: Pete126 on May 27, 2019, 09:03:43 PM
Well that's ruled that out, is this on your 1999 or 1988 126?  the only other thing it could be is the clutch as Gadge suggested, but before you check that are you sure this is not a miss fire at these rev's?
Title: Re: Terrible Engine Vibration
Post by: 5816nick on May 27, 2019, 09:15:46 PM
Hi pete, It's neither my 99 or 88 -  it is a Blitz aircooled 126 based Buggy I Purchased a few weeks ago, i'm not sure of the Year as No Plates were on it when i bought it, i think it's late 70s - I applied for a logbook through the Chassis number -  DVLA  sent me a V5 logbook last Thursday although it hasn't arrived yet.

What would be the best way of checking on a  misfire at 2000 RPM?

It Only Does the Vibration at 1700-2000 revs, Tickover is fine and 2500 RPM is fine.

Kind Regards Nick
Title: Re: Terrible Engine Vibration
Post by: Pete126 on May 27, 2019, 09:53:02 PM
Arhh, if it has a conventional distributor check points/condenser then try slackening it off so it grips but you can still move it, start it when it starts vibrating move the distributor and see if by moving it slightly you can make the engine run smooth, a photo of the engine would be good
Title: Re: Terrible Engine Vibration
Post by: 5816nick on May 27, 2019, 10:12:46 PM
Hi Pete, i'm changing the points and condensor tomorrow, i'll upload some photos on here ASAP

i'll try moving the Dizzy when the vibration starts and see what happens.

Kind regards Nick
Title: Re: Terrible Engine Vibration
Post by: 5816nick on May 29, 2019, 10:28:23 PM
Well, Today i replaced the - Points / Condensor / Leads / Plugs / Carb Stripped / Rebuilt / Valve clearances Checked / Compressions checked and 110 PSI on One Cylinder and 95 on the other..... and still the engine vibrates terribly....at 1700 - 2200 RPM.... I don't know what else to do?

Does anyone have any ideas?
Title: Re: Terrible Engine Vibration
Post by: Pete126 on May 30, 2019, 12:15:21 AM
I’ve run out of ideas what carb is on the car?
Title: Re: Terrible Engine Vibration
Post by: michaelodonnell500 on May 30, 2019, 11:47:18 AM
It is always a good idea to check through all the standard items first. However large vibration issues are rarely fixed by swapping small parts.

I would suspect that your engine has been stripped and rebuilt incorrectly. I purchased a second hand engine from someone who had given up on it because it was vibrating so badly. The vibrations were so bad the tinware had split in several places which he repair welded a few times before giving up on the engine.

When I took the engine apart there was about 2mm of end to end crankshaft float. Another second had engine might be a good idea if you want to get it running again quickly
Title: Re: Terrible Engine Vibration
Post by: 1973/126 on May 30, 2019, 06:19:10 PM
 Have you got any photos of the engine mount. If it is assembled incorrectly it could cause vibration. Also the Blitz buggy is much lighter which probably makes the vibration more noticeable.
 If everything else is ruled out on the outside of the engine, the next thing would be to check the internals.
Title: Re: Terrible Engine Vibration
Post by: Bar Vitelli on May 30, 2019, 08:19:27 PM
I recently had a crankshaft issue on one of my cars, when it idled there was no vibration/rattle, when it revved it made a loud vibration rattle. The only thing that does not match with your description is that you say your car does not vibrate at higher revs.

When the car vibrates does it feel like the vibration is coming from the engine or is the engine causing another part of the car to vibrate?  If its not coming directly from the engine it might be worth checking the gearbox mounts and the gearbox cradle. If the cradle is fitted too tightly that could cause a vibration.
Title: Re: Terrible Engine Vibration
Post by: Gadge on May 30, 2019, 09:57:58 PM
I'm still putting money on the flywheel area. If the spigot is worn or perhaps the input shaft bush then the input shaft (on which the clutch plate is on) can oscillate around so what happens is that the clutch doesn't sit squarely in the centre between the pressure plate and flywheel and so tries to spin the gearbox in an eccentric manner. Obviously the gearbox can't move independently to the engine because it's attached to it so the whole thing starts to move around. Having a spring for an engine mount doesn't help either making the vibration worse.

Years ago I had an almost identical problem except I had the vibration as I tried to take up drive in first but the vibration was so vicious that it felt like the engine was climbing out the car! A new spigot bush cured it completely. It of course may not be this, but to cause that much vibration it must be a mechanical imbalance rather than poor running.
Title: Re: Terrible Engine Vibration
Post by: 5816nick on June 02, 2019, 07:43:18 PM
Hey Guys Thanks for all the Replies, i found an exploded view of the Engine mounting on the very helpful subscribers area on here.... Thanks!

I am waiting for the top hat top washer and bush (Which are both missing....) Hopefully they will come tomorrow.... although as it was still vibrating badly with the main engine mounting taken  off - i don't think it's this....

I took the starter motor off yesterday and see that the flywheel moves very very very slightly, maybe that is loose?
I  am preparing myself to take the engine out next weekend....

The engine Vibrates at 1700-2200 RPM  but then it resonates extremely badly through the rest of the car....

I've tried uploading photos on here but it keeps saying the file is too large.....

Does anyone have a spare 604cc engine they want to sell, i'm imagining worst case scenario.....
I found out the 126 was originally a 1977 model, although i'm still waiting for the logbook.... it's now reay to hit the road, apart from the vibration and logbook issues.....
Title: Re: Terrible Engine Vibration
Post by: michaelodonnell500 on June 03, 2019, 09:29:26 AM
When you say the flywheel moves very slightly, can you be more specific?
Is it rotating? moving end to end? moving side to side?

If you're lucky, maybe the flywheel is loose. If you take the sump off you can check if the crank is moving as well.
Title: Re: Terrible Engine Vibration
Post by: 5816nick on June 09, 2019, 09:29:29 PM
Thanks to all the replies Guys!

The problem turned out to be, the bottom rubber to the Engine mounting was put on upside down by the previous owner and one spacer washer was missing!

The 126 Buggy was originally made in 1977 and is MOT/Tax Exempt and  has been driven on the road for the first time since 1996 today!
Title: Re: Terrible Engine Vibration
Post by: michaelodonnell500 on June 10, 2019, 09:23:28 AM
That's must be a big relief!
Good work getting to the bottom of it!
Title: Re: Terrible Engine Vibration
Post by: Ricksy1121 on June 12, 2019, 09:13:18 PM
Good info here, have a mid range vibration in mine though not as bad as yours sounded but the engine has been out before so will try adjusting the engine mount before digging any further 👍🏻
Title: Re: Terrible Engine Vibration
Post by: 5816nick on June 13, 2019, 10:47:18 AM
Thanks Mike! it is a relief! i'm looking forward to driving it, when it stops raining!

Ricksy, do you have your engine mount lower / upper rubbers on the right way around and the plastic bush/ spacer and 2 metal  washers in the right order? This was the problem with mine, the lower rubber was not present initially, as i had bought it off the previous owner who had put it together wrong ( I thouht it was right / and it looked right - double check the one manual on the subscribers page, there is an accurate and clear picture)

Kind regards Nick
Title: Re: Terrible Engine Vibration
Post by: Ricksy1121 on June 13, 2019, 08:34:53 PM
Thanks, it’s away getting a few rust issues sorted at the moment so when I get it back I will get onto it 👍🏻
Title: Re: Terrible Engine Vibration
Post by: Ricksy1121 on June 22, 2019, 03:58:33 PM
So with the engine running and the inspection cover off the flywheel you can see the flywheel isn’t running perfectly true, there’s a slight wobble in it I’m going to assume this could be the problem, the engine is out and it looks like the holes are towards the head when the pully is at tdc, it’s difficult to determine if the rattle is from the bottom end or the flywheel area of the gearbox. The noise isn’t there at idol and the engine sounds nice it’s once it’s in the mid range it develops the vibration, does anyone know if the bottom end has gone would it sound ok at idol or not. Many thanks 🙏🏼
Title: Re: Terrible Engine Vibration
Post by: DEYAN IYI on June 22, 2019, 04:32:43 PM
Are the moving parts original or modified and in both cases are they balanced and dynamicaly together?
Title: Re: Terrible Engine Vibration
Post by: Ricksy1121 on June 22, 2019, 04:56:48 PM
It all looks original but I got the engine second hand so know nothing about it unfortunately
Title: Re: Terrible Engine Vibration
Post by: Ricksy1121 on June 22, 2019, 06:33:57 PM
Is this the correct position for tdc and the flywheel holes please

Sorry the pictures have turned round when I uploaded them, I can’t work out how to correct it

<a href="https://imgshare.io/image/SOG2F"><img src="https://imgshare.io/images/2019/06/22/A9D04F77-2E34-4F55-8160-44223CEAC722.md.jpg" alt="A9D04F77-2E34-4F55-8160-44223CEAC722.md.jpg" border="0"></a>
<a href="https://imgshare.io/image/SOkLn"><img src="https://imgshare.io/images/2019/06/22/3A1D483D-E75A-48CD-95FD-FC6763504B6A.md.jpg" alt="3A1D483D-E75A-48CD-95FD-FC6763504B6A.md.jpg" border="0"></a>
Title: Re: Terrible Engine Vibration
Post by: Gadge on June 22, 2019, 06:41:19 PM
Nearly right its on 10 degrees before TDC. To get TDC you need to align the pulley mark with the big pointer
Title: Re: Terrible Engine Vibration
Post by: Ricksy1121 on June 22, 2019, 06:51:27 PM
Ok thanks, so is that the flywheel correct with the round indent pointing towards the head?
Title: Re: Terrible Engine Vibration
Post by: Ricksy1121 on June 22, 2019, 09:33:05 PM
Took the flywheel off and put it back on, started it up and it ran true no side to side motion like it had before 👍🏻 Maybe someone bolted it up without using the old cross method so didn’t seat correctly. Hopefully sorted now, will come out again tomorrow to continue with the restoration.
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