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-   -   VW 1.6TD Engine Off Coasting (https://ecomodder.com/forum/showthread.php/vw-1-6td-engine-off-coasting-36274.html)

Hic 03-20-2018 07:05 AM

VW 1.6TD Engine Off Coasting
 
The service manual for my MK2 1.6TD VW states that damage may occur if towing on the drive wheels at speeds greater than 80kph/50mph. Does this mean engine off coasting above 80kph is harmful for the transmission? I thought only automatic transmissions see damage from engine off coasting. Is this transmission in particular incompatible with high speed engine off coasting? Or is engine off coasting normally not used at these speeds? I've pulsed and glided regularly between 70~110kph on this car for almost 2 years now...should I be concerned about transmission damage?

Ecky 03-20-2018 03:00 PM

My guess is that the manual is in error, or didn't differentiate between the manual and automatic. However, don't hold me responsible for any damage that occurs. :p

Fingie 03-20-2018 04:05 PM

i think it's rather for the safety of towing a car, as towing a car is generally more unstable at higher speeds. A manual box shouldnt give a damn

Piwoslaw 03-20-2018 04:20 PM

Or maybe it means that towing has not been tested above 80kph, so VW only ensures the safety up to that speed?

Hic 03-21-2018 10:13 PM

Mmm they specifically say it could cause damage to the gearbox. They also mentioned that automatics should not be towed on the drive wheels at all, so the advice for towing at 50mph/80kph+ is intended for manual gearboxes.

There is no restriction of towing speed mentioned when towing on the rear wheels, so this is related to the longevity of the gearbox, rather than the safety of towing at highway speeds (or whether they've tested it to ensure).

iikhod 03-22-2018 02:35 AM

I would be more concerned about shutting off your turbo engine hot, with the turbo spinning wild after your pulse :confused:

COcyclist 03-22-2018 10:37 AM

Quote:

Originally Posted by iikhod (Post 564483)
I would be more concerned about shutting off your turbo engine hot, with the turbo spinning wild after your pulse :confused:

X2. With my diesel Golf I only E-On coast (which I do a lot). With the key off you lose not only oil circulation to the turbo but also airbags, ABS, power steering and eventually brake boost, and it messes up my ScanGuage:mad:. In my experience you will not hurt your transmission from coasting briefly, even at higher speeds. Towing a car could conceivably be done over great distances and time, which may eventually do damage.

Hic 03-22-2018 11:23 PM

Quote:

Originally Posted by COcyclist (Post 564495)
X2. With my diesel Golf I only E-On coast (which I do a lot). With the key off you lose not only oil circulation to the turbo but also airbags, ABS, power steering and eventually brake boost, and it messes up my ScanGuage:mad:. In my experience you will not hurt your transmission from coasting briefly, even at higher speeds. Towing a car could conceivably be done over great distances and time, which may eventually do damage.

Hmm, I want to keep this thread on topic to the question of whether the transmission will see harm.

iikhod 03-23-2018 09:38 AM

If EOC at those speeds would harm your gearbox, probably would have broken something by now.
How much you save fuel with EOC compared to coasting with the engine running? Just out of curiosity.

Hic 03-23-2018 09:53 AM

Quote:

Originally Posted by iikhod (Post 564564)
If EOC at those speeds would harm your gearbox, probably would have broken something by now.
How much you save fuel with EOC compared to coasting with the engine running? Just out of curiosity.

The damage may be insignificant over the short term. It's like saying shutting off after a pulse doesn't hurt the turbo because my turbo is still fine.

I'm not sure how much the savings are.

iikhod 03-23-2018 11:32 AM

Quote:

Originally Posted by Hic (Post 564567)
The damage may be insignificant over the short term. It's like saying shutting off after a pulse doesn't hurt the turbo because my turbo is still fine.

I'm not sure how much the savings are.

Are you somehow offended because i mentioned the thing about the turbo earlier in the thread or what?
I can assure you i didn't mean to offend anyone. :thumbup:

Ecky 03-23-2018 11:38 AM

Quote:

Originally Posted by COcyclist (Post 564495)
X2. With my diesel Golf I only E-On coast (which I do a lot). With the key off you lose not only oil circulation to the turbo but also airbags, ABS, power steering and eventually brake boost, and it messes up my ScanGuage:mad:. In my experience you will not hurt your transmission from coasting briefly, even at higher speeds. Towing a car could conceivably be done over great distances and time, which may eventually do damage.

Sounds like you need an injector kill switch. :thumbup:

Hic 03-23-2018 11:40 AM

Quote:

Originally Posted by iikhod (Post 564572)
Are you somehow offended because i mentioned the thing about the turbo earlier in the thread or what?
I can assure you i didn't mean to offend anyone. :thumbup:

I'm not sure where you got the offended part. I'm merely pointing out the inconsistency in your logic.

Anyways, let's keep this thread on topic - VW's claim that the gearbox may see damage.

ksa8907 03-23-2018 11:53 AM

Quote:

Originally Posted by Hic (Post 564567)
The damage may be insignificant over the short term. It's like saying shutting off after a pulse doesn't hurt the turbo because my turbo is still fine.

I'm not sure how much the savings are.

The savings are insignificant in the face of possible damage. Engines usually idle around 0.25 gallons, roughly 1 liter, per hour. So if you spend 10 minutes coasting, the difference between on and off is 0.05 gallons or 0.1 liters.

The money difference is insignificant.

Hic 03-23-2018 12:01 PM

Quote:

Originally Posted by ksa8907 (Post 564576)
The savings are insignificant in the face of possible damage. Engines usually idle around 0.25 gallons, roughly 1 liter, per hour. So if you spend 10 minutes coasting, the difference between on and off is 0.05 gallons or 0.1 liters.

The money difference is insignificant.

Hmm, perhaps I wasn't clear enough, but I'm curious if this does indeed harm the gearbox, and how it does so. I am interested in the mechanical ongoings. Whether one should engine off coast is a separate issue that I don't want confused with the topic. Same with whether other components in the car may be damaged, or the risks of engine off coasting, these are off topic.

me and my metro 03-23-2018 01:50 PM

Some manual transmissions pump or circulate lube oil when driven by the engine. Some manual transmissions lube properly when driven by the road wheels. My Saturn has a F35 Getrag transmission and has no restrictions on flat tow speed or distance. Is there a distance restriction or strictly a speed restriction on your VW trans. It is a lack of lube issue.

Hic 03-23-2018 02:11 PM

Quote:

Originally Posted by me and my metro (Post 564590)
Some manual transmissions pump or circulate lube oil when driven by the engine. Some manual transmissions lube properly when driven by the road wheels. My Saturn has a F35 Getrag transmission and has no restrictions on flat tow speed or distance. Is there a distance restriction or strictly a speed restriction on your VW trans. It is a lack of lube issue.

That makes sense. The manual mentions a limit of both speed and distance.

Hic 03-23-2018 02:52 PM

1 Attachment(s)
Manual

me and my metro 03-23-2018 03:39 PM

I see that you understand what VW is saying. You are fine doing what you are doing, unless you can glide 50 miles at a time. LOL

UFO 03-23-2018 04:21 PM

I agree, it looks like a long-term type of issue. Short periods of EOC should be fine.

Hic 03-23-2018 10:47 PM

Hmm, I believe there's further misunderstanding here. The condition VW provided is a disjunction, not a conjunction. The distance OR the speed will satisfy the condition of harm. It is the speed (rather than distance) that is relevant here. The negation of the distance doesn't mean the conditions necessary for gearbox harm aren't satisfied. That would only be the case if a conjunction (and) was used.

ksa8907 03-24-2018 01:24 AM

Quote:

Originally Posted by Hic (Post 564635)
Hmm, I believe there's further misunderstanding here. The condition VW provided is a disjunction, not a conjunction. The distance OR the speed will satisfy the condition of harm. It is the speed (rather than distance) that is relevant here. The negation of the distance doesn't mean the conditions necessary for gearbox harm aren't satisfied. That would only be the case if a conjunction (and) was used.

So.... Yes, you're damaging the transmission. You shouldn't do that.

Then again, it's a vw so it's probably going to break anyway. :thumbup:

cRiPpLe_rOoStEr 03-24-2018 03:33 PM

Those older manual transmissions rely more on splash lube than pressurized lube, so at least in theory EOC or towing above 80km/h shouldn't do any harm.

Hic 03-24-2018 07:46 PM

Quote:

Originally Posted by cRiPpLe_rOoStEr (Post 564682)
Those older manual transmissions rely more on splash lube than pressurized lube, so at least in theory EOC or towing above 80km/h shouldn't do any harm.

That's what I thought too, so I'm not sure why the manual states otherwise. :confused:

Hic 03-24-2018 10:49 PM

Quote:

Originally Posted by ksa8907 (Post 564642)
So.... Yes, you're damaging the transmission. You shouldn't do that.

Then again, it's a vw so it's probably going to break anyway. :thumbup:

Yes, that is definitely what the manual states. As I've mentioned, "I'm curious if this does indeed harm the gearbox, and how it does so." Since you also agree that it does harm the transmission, how do you suppose it does so?

oldtamiyaphile 03-25-2018 08:28 PM

Your biggest gains from EOC are at speeds below 50 anyway.

cRiPpLe_rOoStEr 03-25-2018 10:24 PM

Quote:

Originally Posted by Hic (Post 564706)
I'm not sure why the manual states otherwise. :confused:

Who knows...

ksa8907 03-25-2018 10:31 PM

Quote:

Originally Posted by Hic (Post 564715)
Yes, that is definitely what the manual states. As I've mentioned, "I'm curious if this does indeed harm the gearbox, and how it does so." Since you also agree that it does harm the transmission, how do you suppose it does so?

Lol, because the mtg said so? I mean, they're only engineers who happened to also design the car so, I guess they don't know what they're talking about....

Likely, the residual oil in the bearings is enough to lubricate adequately UP TO 50 km OR UP TO 50km/hr. Longer distances and higher speeds will run through that residual oil and once gone will cause excessive friction and wear/scoring/gouging on the bearings.

This is one of those times where ymmv. Good luck, not worth the effort and small money saved in my opinion.

cRiPpLe_rOoStEr 03-25-2018 10:35 PM

Maybe you could try and check with those businesses that sell tow hitches for RVs. They usually have a list of what cars are safe for flat-towing and what ones require some preventive measure to prevent damage to the transmission.

UFO 03-26-2018 02:07 PM

Quote:

Originally Posted by ksa8907 (Post 564803)
Lol, because the mtg said so? I mean, they're only engineers who happened to also design the car so, I guess they don't know what they're talking about....

Likely, the residual oil in the bearings is enough to lubricate adequately UP TO 50 km OR UP TO 50km/hr. Longer distances and higher speeds will run through that residual oil and once gone will cause excessive friction and wear/scoring/gouging on the bearings.

This is one of those times where ymmv. Good luck, not worth the effort and small money saved in my opinion.

There are many reasons for the manual to proscribe rolling with the engine off, not all of them having to do with actually damaging the transmission. My opinion, FWIW, is this is more of a safety issue with towing. Does anyone actually observe the speed limit for towing a U-Haul trailer?

And BTW, I don't EOC with my VW. I agree, the savings are not worth the risk for me, heh.

cRiPpLe_rOoStEr 03-26-2018 03:09 PM

Quote:

Originally Posted by UFO (Post 564835)
There are many reasons for the manual to proscribe rolling with the engine off, not all of them having to do with actually damaging the transmission. My opinion, FWIW, is this is more of a safety issue with towing. Does anyone actually observe the speed limit for towing a U-Haul trailer?

Sure, towing has some impact on the driving dynamics that should not be neglected. Anyway, even though an American would be more likely to tow with a beefier vehicle such as a truck or body-on-frame SUV which usually has brakes better dimensioned for such use, in most of other countries you can see regular econoboxes towing sometimes in excess of their GVWR :eek:

Hic 03-28-2018 11:52 PM

Quote:

Originally Posted by ksa8907 (Post 564803)
Lol, because the mtg said so? I mean, they're only engineers who happened to also design the car so, I guess they don't know what they're talking about....

Likely, the residual oil in the bearings is enough to lubricate adequately UP TO 50 km OR UP TO 50km/hr. Longer distances and higher speeds will run through that residual oil and once gone will cause excessive friction and wear/scoring/gouging on the bearings.

This is one of those times where ymmv. Good luck, not worth the effort and small money saved in my opinion.

Hmm, iikhod seems to disagree with you here. Thoughts?

Quote:

Originally Posted by iikhod (Post 564564)
If EOC at those speeds would harm your gearbox, probably would have broken something by now.


LittleBlackDuck 03-29-2018 12:29 AM

Quote:

Originally Posted by cRiPpLe_rOoStEr (Post 564682)
Those older manual transmissions rely more on splash lube than pressurized lube, so at least in theory EOC or towing above 80km/h shouldn't do any harm.

That really depends on whether the splash lubrication depends on the gears driven by the engine to splash up the oil. It will vary lots from one gearbox to another, and the manufacturers generally know best.

cRiPpLe_rOoStEr 03-29-2018 02:59 PM

Quote:

Originally Posted by LittleBlackDuck (Post 565112)
That really depends on whether the splash lubrication depends on the gears driven by the engine to splash up the oil. It will vary lots from one gearbox to another, and the manufacturers generally know best.

Sure, but those older transmissions usually don't rely on the engine to provide that oil splash. Newer ones on the other hand, especially since 6-speeds started taking over the 5-speeds, are more critical on that regard.

Hic 03-29-2018 10:24 PM

Quote:

Originally Posted by cRiPpLe_rOoStEr (Post 565169)
Sure, but those older transmissions usually don't rely on the engine to provide that oil splash. Newer ones on the other hand, especially since 6-speeds started taking over the 5-speeds, are more critical on that regard.

Ah that's what I was suspecting as well.

cRiPpLe_rOoStEr 03-30-2018 12:26 AM

Some companies such as Remco Industries provide auxiliary lube pumps to prevent transmission damage while flat-towing, and AFAIK there is no such pump available for use in the 5-speed transmission fitted to the Golf. They claim it's safe to flat tow at up to 65MPH according to the manual, but don't give further details.


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