Fiat Marea reverse gear is growling, thicker oil?

[Popsy]

Guys,

For a few months now the reverse gear in my Fiat Marea (cf sig) is sometimes growling - sometimes perfectly silent, but it is more and more growling and it sure won't fix itself...

It is randomly happening (more and more frequent though), cold or hot. Others gears are perfectly ok and operation is smooth.

To see if it can be easily/temporarily fixed, I changed the oil with Mobil 1 SHC 75W90 (previous oil was Motul Motylgear 75W90 which is semi-synth), and it only made things worse. I have a feeling the Mobil 1 oil is more fluid (I know), and that's part of the problem.

Do you think a thicker oil could correct the problem a bit? Like some 75W140 oil?

I can find used gearbox for ~300€, but they come without warranty...I don't like the lottery much so maybe if something could improve the situation.

PS: I have some Castrol Syntrax Universal Plus 75W90 in my stash, but I don't think it will do anythink more than the Mobil 1.
I went to some local garage and they told me to put some additive, I checked the additives in question and they were Teflon or MoS2 additive, oriented to noisy and/or difficult gearchanges (worn out synchromesh), wich my gearbox doesn't do.

Edit: Sorry, post is in the wrong section! Can a mod move it? I was reading in the section and didn't pay enough attention, sorry again, can't delete my post

 

[LubeLuke]

Most vehicles have straight cut reverse gears. The sound of these gears can be described as 'growling'.

 

[Popsy]

Sure...but it is a new and abnormal noise, it wasn't growling before.
I have another Fiat with similar gearbox, perfectly silent in reverse. Maybe "growling" isn't the best description for the noise though

 

[bigt61]

239,000 miles and now it's growling in reverse? I'd certainly demand a refund. Jeez, unless you're spending half the day driving in reverse, I'd just live with it until it breaks. Put some fresh fluid in and call it a day.

 

[supercity]

Mechanical problem, not lubrication. thicker oil is unlikely to do anything.

 

[ARCOgraphite]

I toasted the reverse in my 3P backing up my friends driveway "vigorously"; the gear was the size of something in a clock or small toy robot. As kid , I Was used to a indestructable buick turbo400. The Fiat was a bit lighter duty ... to say the least.

 

[chrisri]

Your gearbox is fine. You have problems with clutch pressure plate. It's worn out, specifically your diaphragm springs are worn. When you press clutch thrust bearing can't release fully clutch disc, and that's why it grinds. Reverse is not synchronised so it's more pronounced when engaging reverse.

 

[Popsy]

lol, thanks for answers.

chrisri, clutch disc and mechanism have been replaced at ~180K, do you really think it can already be faulty?

Also it is grinding not while engaging reverse, just when going forward, the faster I go, the louder it is.

I'm not really worried since this car is not worth anything, just curious of what can be faulty/dying.

 

[expat]

"
Also it is grinding not while engaging reverse, just when going forward, the faster I go, the louder it is."

Going forward while in reverse ould cause problems

But seriously, make sure the oil level is full, or just change it for new.

 

[Jetronic]

you could try the MoS2 additive to quiet it down.

The castrol oil might have an ester base.

Can youi find the correct spec oil for your gearbox? Some Fiat boxes spec GL-5, others GL-4. Big difference. You won't find a 75w-140 GL-4 I think...

 

[Popsy]

Manual says GL-4 oil, I suspect the gearbox has some yellow metal parts, but Mobil 1 SHC 75W90 is GL4 and GL-5 so should be ok.

Also the drain plug has a magnet, and there was not much stuck to it when I did the OC.

You're right about GL-4 compatible 75W140 oil, I've only found IGOL Rallye Gear 80W140 which is GL-4, not much information about it.
Originally Posted By: expat
"
Going forward while in reverse ould cause problems

But seriously, make sure the oil level is full, or just change it for new.

Lol, bad English, sorry

Like I said above, level is full and oil is new. It is actually worse with the new oil.

Do you think it's worth to drain the Mobil oil (in a clean container), and put some Castrol in it? or just a loss of time?

 

[Jetronic]

I wouldn't use a GL4-5 rated oil, byut a GL3-4 is likely ok. We have some experience wit that at work. Nothing is likely to break, but shifting suffers.

 

[chrisri]

Originally Posted By: Popsy
lol, thanks for answers.

chrisri, clutch disc and mechanism have been replaced at ~180K, do you really think it can already be faulty?

Also it is grinding not while engaging reverse, just when going forward, the faster I go, the louder it is.

I'm not really worried since this car is not worth anything, just curious of what can be faulty/dying.

Oh OK, I was under impression that your reverse grinds on engaging, and not while driving. Reverse whine is normal.

Fiat C510 and C514 gearboxes used GL5 75w80/90 MTFs.

 

[Popsy]

Actually I'm not 100% sure of tha API rating the gearbox calls for, and Fiat does all it could to misguide you if you don't buy the appropriate Selenia/Tutella oil!
Chriscri advides GL5 oil like Motul gear 300 for this type of gearbox in the past.

Out of curiosity, what a GL3/GL4 can do a GL4/GL5 can't? Is it based on experience, or something else (this is a real question)?
A few years ago I've briefly used Some Total GL4+ oil in this gearbox, and it was a total (pun not intended) disaster (plus its smell was awful), but if you have some brand in particular to advise?

Edit: burned.

Like I stated, the noise in reverse is quite new and completely different from the normal "reverse" grinding. i have this car since its 40000K, and also a Barchetta, i think I can differentiate normal from abnormal noise, lol!

 

[chrisri]

GL5 MTF contains more EP additives that are necessary for hypoid gears in those gearboxes.
Never use GL4 fluid in a GL5 gearbox, opposite is true also. Fiat spec Tutela ZC 75 synth in those.
I've found Motul Gear 300 to work best in them, better than Tutela.

 

[Popsy]

Ok. The manual calls for GL4 and/or MIL-L-2105 oil (Tutela ZC75 SYNTH), it is a C510 gearbow, like you said. I can try Motul hear 300 if you say it is not a waste of time and money and could improve the noise.
I'm afraid the noise is caused by a shot bearing, but why only in reverse?

 

[expat]

Just a thought. Are you sure it's the transmission not the differential?

I have had Diff whine in reverse but not forward.

 

[Jetronic]

It's the diff that would suffer most if you used a GL-4 oil in a box that calls for GL-5...

 

[Popsy]

Maybe you're right and it's the diff making noise. I'd prefer that, I think!

Maybe it is actually temperature related, Today was a warm and sunny day and no noise from the diff/gearbox

 

[Jetronic]

or the stones worked themselves out of the tyre thread