Technical 1991 Croma 2.0T i.e. in USA - tips on timing/balance shaft belts

[entirelyturbo]

Hello everyone,

I recently imported a pristine-condition 1991 Fiat Croma 2.0T i.e. to the United States.

It runs and drives fine, but it has a troubling whining noise coming from the timing belt area, which I suspect is a timing belt tensioner. I've hardly driven it at all since taking delivery, so no permanent damage has been done.

I'm reasonably mechanically inclined, and have serviced other vehicles' timing belts before (mostly Subarus). I already have the parts en route to me from Europe as we speak.

I've never serviced a Lampredi Twin Cam before though (for obvious reasons).

Does anyone have experience servicing the timing belt and balance shaft belts on these cars, or any other car with a transversely-mounted Lampredi Twin Cam (like a Lancia Delta, for example) that could offer me some tips? Any idiosyncrasies I should be aware of?

Thanks for any help, and below is a picture of my Croma the night I took possession of it:

 

[bugsymike]

Hello everyone,

I recently imported a pristine-condition 1991 Fiat Croma 2.0T i.e. to the United States.

It runs and drives fine, but it has a troubling whining noise coming from the timing belt area, which I suspect is a timing belt tensioner. I've hardly driven it at all since taking delivery, so no permanent damage has been done.

I'm reasonably mechanically inclined, and have serviced other vehicles' timing belts before (mostly Subarus). I already have the parts en route to me from Europe as we speak.

I've never serviced a Lampredi Twin Cam before though (for obvious reasons).

Does anyone have experience servicing the timing belt and balance shaft belts on these cars, or any other car with a transversely-mounted Lampredi Twin Cam (like a Lancia Delta, for example) that could offer me some tips? Any idiosyncrasies I should be aware of?

Thanks for any help, and below is a picture of my Croma the night I took possession of it:
View attachment 465161

Is this your Engine Series.?

 

[entirelyturbo]

Is this your Engine Series.?

I'll double-check my engine code later, but everything I see there indicates that's my engine.

That's a huge help! Thank you bugsymike!

I've read something elsewhere on this forum about Tempras that the crankshaft pulley/harmonic balancer bolt is reverse threaded... do you see any note of that in your manual?

 

[bugsymike]

I'll double-check my engine code later, but everything I see there indicates that's my engine.

That's a huge help! Thank you bugsymike!

I've read something elsewhere on this forum about Tempras that the crankshaft pulley/harmonic balancer bolt is reverse threaded... do you see any note of that in your manual?

Looking at the same manual it seems like the crank pulley stays on and you just under the smaller bolts and then retorque to 25Nm at number one in bottom of photo.

 

[entirelyturbo]

So the diagram was indeed helpful as far as getting the marks lined up, I was a bit lost on the correct placement for the cam marks until I paid very close attention to it.

My engine code is 154C4, so a bit updated from that workshop manual.

For example, i had to remove the front crank pulley for the accessory belts, there's no way to service the timing belt without removing it, which means I was able to confirm like I saw elsewhere on this forum that the big crank pulley bolt IS in fact a reverse thread. I'm glad I didn't learn that the hard way!

Anyway, I got the timing belt and balance shaft belt replaced...

... and after turning two crank revolutions, I bravely started it up briefly and it started right up and ran fine. So the timing is correct.

However, I think I'm unable to put sufficient tension on the timing belt since I don't have the tool that appeared in your picture from the workshop manual, bugsymike.

[

... so I think the timing belt is walking back and forth and occasionally hitting the balance shaft belt and making a horrendously unnerving noise.

The car is not my daily driver, so it's safely parked in my garage and will not be driven until I can get to it again.

Does anyone happen to know where I can procure that tool or is there a way I can fabricate my own? I've looked at universal tensioner tools on eBay and I don't think they will work with this configuration.

 

[bugsymike]

As @Pugglt Auld Jock mentioned in another post regarding similar tensioner adjuster, we have both used right angled circlip pliers in the two holes with success and gone by the feel of the belt tension. Obviously rechecked after running etc.
Another point is it may not be the tension that is causing the "walking" issue, normally the guides on the edges of the camshaft pulleys would keep that belt in line.
Your outer belt should be kept in place by the auxilary belt's pulley as a guide, I would have thought.
Many years ago I was watching one "walk" as you describe and luckily switched engine off when I realised the back of the missing outer pulley had a purpose.
I see what you meant about your later version with the balance shafts etc. A much more involved set up.
A bit late now, but based on your engine series number I have just found this.

 

[s130]

Does anyone happen to know where I can procure that tool or is there a way I can fabricate my own? I've looked at universal tensioner tools on eBay and I don't think they will work with this configuration.

I've used two M6 cap head bolts inserted into the two holes in the tensioner and screwdriver / bar as a lever between them.

 

[entirelyturbo]

So, several months later... I finally was able to mess with it again...

... after removing the balance shaft belt and then starting it briefly as part of the diagnosis, the whining noise I was hearing when I first got the car did indeed disappear entirely with the balance shaft belt missing.

so, by process of elimination, the noise is definitely one of the balance shaft bearings

So, now I get to remove the engine



I'm assuming removing the balance shafts is an engine-out affair, right? I don't see how it could not be with the left (front, lower) balance shaft bearing appearing to be in the transmission bellhousing according to the parts catalog.

It has a rear main seal leak anyway, so this will be an opportune time to fix that.

So, has anyone here replaced balance shaft bearings before?

I don't want to run the engine without the balance shafts... I know a balance shaft delete is common on Lampredi Twin Cam engines, but I would like to keep it as original and as functional as it was from the factory as possible. Longevity is important to me, too.

 

[entirelyturbo]

@bugsymike you've been extremely helpful so far... does the manual you have show any procedures for removal and reinstallation of the balance shaft?

 

[bugsymike]

@bugsymike you've been extremely helpful so far... does the manual you have show any procedures for removal and reinstallation of the balance shaft?

Sorry no, my books are technical manuals for the motor trade and details of timing marks etc. for the cam belts and my other manuals deal with torque settings etc. But in general terms they are designed for use by fully skilled mechanics who only need those details to do the job based on their experience on working on a variety of vehicles.
Is the engine out or are you trying to work in situ?
What was the reason for balance shaft removal?

 

[entirelyturbo]

I've attached two videos, the first video is from the day I got the car, and while it's running, you can hear a distinct whirring/whining noise coming from the engine (that was directly RPM dependent), which I first figured was a timing belt idler/tensioner issue.

But after a timing belt service didn't fix the problem, I removed the balance shaft belt and started it naked (with no belt attached other than the camshaft timing belt) and the noise completely disappeared, as evidenced in the second video.

Hopefully the attachments work properly. I shortened them considerably to minimize the file size.

So a simple process of elimination dictates it has to be one of the balance shaft bearings, and since it's a whining noise rather than a knocking noise, I feel safe in diagnosing it as one of the roller bearings on the end of one of the balance shafts and not the center support bearings (although I intend to replace any and all bearings associated with the balance shafts).

And I don't see how to service the rear roller bearings, on the back of the engine, with the engine or transmission in place because it looks like they're inside the transmission bellhousing, according to the attached parts diagram.

The engine has not been removed yet, but I intend to remove it to do this (and replace the leaking rear main seal).

But thank you anyway, @bugsymike I have some degree of experience turning wrenches and friends who are willing to offer guidance, so I'll get it figured out.

 

[bugsymike]

I've attached two videos, the first video is from the day I got the car, and while it's running, you can hear a distinct whirring/whining noise coming from the engine (that was directly RPM dependent), which I first figured was a timing belt idler/tensioner issue.

But after a timing belt service didn't fix the problem, I removed the balance shaft belt and started it naked (with no belt attached other than the camshaft timing belt) and the noise completely disappeared, as evidenced in the second video.

Hopefully the attachments work properly. I shortened them considerably to minimize the file size.

So a simple process of elimination dictates it has to be one of the balance shaft bearings, and since it's a whining noise rather than a knocking noise, I feel safe in diagnosing it as one of the roller bearings on the end of one of the balance shafts and not the center support bearings (although I intend to replace any and all bearings associated with the balance shafts).

And I don't see how to service the rear roller bearings, on the back of the engine, with the engine or transmission in place because it looks like they're inside the transmission bellhousing, according to the attached parts diagram.

The engine has not been removed yet, but I intend to remove it to do this (and replace the leaking rear main seal).

But thank you anyway, @bugsymike I have some degree of experience turning wrenches and friends who are willing to offer guidance, so I'll get it figured out.

Quite a noise.
By the way in case you mis understood I wasn't being derogatory re your rebuilding skills, it is just they are not manufacturers repair/rebuild manuals specific to that engine, they cover most common vehicles at the time but only one or two pages on each model of things like torque settings etc. that the trade relied on
Re the noise, have you definately located it at the rear roller bearing area? The reason I ask, is looking at your last photo of engine block it indicates housings or ports above balance shaft that may in a different version been used to drive something, possibly distributor or fuel pumps etc. at a guess.
Have you been able to use a stethoscope or long screwdriver to your ear to pinpoint the exact area of the noise, to confirm it being that rear bearing. If so it does look like gearbox, flywheel and engine back plate would need to be removed to gain access.
I have no accurate information about the type of bearing, if it is a roller type as that surprises me as most engine internal shafts are "white metal" bearings, in which case they would need specialised tools to drive out the old ones and replace with new and then quite possibly those new bearings would need to be line bored in the block to be centralised.
I can see why an accurate factory manual would be very useful.

 

[entirelyturbo]

@bugsymike oh no, no derogatory intent was perceived Don't worry.

Are those manuals you have not OEM Fiat service manuals? They appear to be too specific and detailed (torque specs, etc.) to be a generic manual like a Haynes/Chilton manual.

I'm unsure of what the design of the original external balance shaft bearings are, since I haven't disassembled the car yet, but I know the OEM replacements I've procured are definitely of a roller bearing design, as pictured in the attachments.

The part number has superseded too, so maybe Fiat decided a design change was necessary to the bearings.

I think I will be using my stethoscope to try to identify the individual faulty bearing(s), and hopefully it's just an external roller bearing making the noise and I can replace just those 4 external bearings and fix the car with no further intrusion into the engine block. As you mentioned, I would imagine a center shaft bearing replacement would require an entire engine overhaul and a trip to the machine shop for the bare block, which I don't want to do because the engine runs excellent other than this issue and I have learned in my years not to fix something that isn't broken.

 

[bugsymike]

@bugsymike oh no, no derogatory intent was perceived Don't worry.

Are those manuals you have not OEM Fiat service manuals? They appear to be too specific and detailed (torque specs, etc.) to be a generic manual like a Haynes/Chilton manual.

I'm unsure of what the design of the original external balance shaft bearings are, since I haven't disassembled the car yet, but I know the OEM replacements I've procured are definitely of a roller bearing design, as pictured in the attachments.

The part number has superseded too, so maybe Fiat decided a design change was necessary to the bearings.

I think I will be using my stethoscope to try to identify the individual faulty bearing(s), and hopefully it's just an external roller bearing making the noise and I can replace just those 4 external bearings and fix the car with no further intrusion into the engine block. As you mentioned, I would imagine a center shaft bearing replacement would require an entire engine overhaul and a trip to the machine shop for the bare block, which I don't want to do because the engine runs excellent other than this issue and I have learned in my years not to fix something that isn't broken.

These types of manuals are what I have used in the Motor Trade sinece 1969 starting with the red Palgrave Publishing ones and then superceeded by the Auto Data Versions, so not manufacturer specific, my last ones were in 2012 at around £100 + Vat, as I was retiring soon after I didn't buy any more new as Auto Data then went to DVDs and subsequently Online only at great expense and time expired so I preferred my manuals which will out live me at no extra cost. Although the Online stuff has even greater detail and some instruction and known faults etc. to help todays mechanics.
You do see these manuals on eBay etc. and occasionally at AutoJumbles if you keep your eye open.
You will notice my manuals are not in "showroom condition", my College Lecturer was of the mind that technical information was to be used by the mechanic, not left in the bosses office to be pulled out to show details by the secretary on the odd occasion.
Hopefully your balance shaft is only supported on the roller bearings and once replaced will need no other attention.
The stethoscope should help , but I agree a nice photo of the item in a OEM service manual would be best, apart from in garage auctions in the late 80s when companies wqere going bust due to the recession those manuals don't come up very often.
As I started my apprenticeship at a garage that worked on anything that came through the door I have been lucky to get a wide range of knowledge, even if I am now forgetting most of it , I had friends who worked for dealerships and any other makes of vehicle they didn't know where to begin with.
I used to say in any one day I could be doing a service on a Mk 1 Ford Cortina, fix the bosses outboard engine, weld an old ladies shopping trolley up, make up and fit new metal brake pipes on an XK140 Jaguar and do the puncture on a farmers muck spreader with split steel rims, so never afraid to tackle anything. It even helped when a computer shop tried to rip me off, I taught myself how to repair computers from 286s onwards as largely locating a fault and installing a new circuit board or hard drive etc. No programming, as beyong me, although one of my sisters made her carear out of that.