Weak cruise control on an auto box KV6

Dorchester2 · 23rd March 2023, 06:50

Is there anyone here experiencing a weak CC on an auto KV6?
Very recently I noticed that my cruise control was apparently working - light on switch, speed locked at the wheel then pedal automatically pressed - but it looks a bit hard to maintain the speed and slightly and slowly loosing speed. But if I do a long pull on the "set+" wheel control, the engine is once more able to accelerate by itself and I can release the button at the speed required. But progressively loosing speed again after a short while.

I am now suspecting a leak in the vacuum pump.
But I can't find any new from old stock as we say. All vacuum pumps available are used ones from Range Rover P38 same era and look similar as the one I may need but the plug which isn't the same.

Your help would be greatly appreciated because suffering from sciatica since years, that cruise control is vital to put my legs at rest on a long trip.
Thanks a lot.

dave lincs · 23rd March 2023, 08:14

Check the vacuum unit on the throttle body I have had few of those leak

stocktake · 23rd March 2023, 08:35

Almost certainly what Dave diagnosed, the bellows or the push on pipe that connects to it.

Dorchester2 · 23rd March 2023, 10:56

Thank you.
But which piece are you precisely talking about?
Is it what Rimmer's call the Actuator Ass(embl)y SCC100110L (item #3)?
https://rimmerbros.com/Item--i-GRID001952

stocktake · 23rd March 2023, 13:27

Item three in your diagram is the vacuum assembly, it works on a vacuum being pulled. They can leak air or the pipe that connects to the unit develops tiny leak therefore slowly losing the vacuum.

Dorchester2 · 23rd March 2023, 14:07

Thank you buddie.
Hence which of the two I've shown should be the culprit ?
And how to cure the problem ?
By a repair (which ? ) or a swap ?
Thanks a lot. I'm so dumb I need to be sure.

stocktake · 23rd March 2023, 16:51

https://rimmerbros.com/Item--i-GRID001952

Item 3
SCC100110L

search by part number there may be cheaper sellers.

There are no electrical connections on this part it simply holds a vacuum

https://www.bing.com/images/search?v...t=0&ajaxserp=0

BUT FIRST:
Check the push on pipe hasn't split/come loose, lot cheaper to replace.

There are also 2nd hand throttle bodies on ebay including this part but it's not saving much
https://www.ebay.co.uk/itm/393995464...kAAOSwGuViNzM0

Dorchester2 · 23rd March 2023, 16:54

Thank you so much Dave.

It's crystal clear.
But there isn't a single "SCC100110" available on Ebay.
Only Rimmer's...

Dorchester2 · 24th March 2023, 09:20

I may have found the same one for a better price at Allbrits'.
50.19 € instead of 66.34 € at Rimmers'.
And no import duties for us on the continent as they are located in Germany.
I've just ordered and am waiting for their invoice.
https://allbrit.de/xepc.cfm?PAGE=138...E=DE&CAR=SARRJ

Dorchester2 · 25th March 2023, 19:14

End of story...

1. Germans' knavish trick: Allbrits claimed that they had no more any SCC100110 for Rover 75 at 50€, but that they could provide me with SCC100110L for Land/Range Rover (and Rover 75 100% compatible!) at 76€!!!

Easy: it's exactly the same item!

Anyway I'd ordered one for peace of mind.

2. I came to my mechanic's this morning to cure my coil & plug problem (see my post https://www.the75andztclub.co.uk//fo...12&postcount=1).
In the end I told him every little detail about my CC weakness.
He asked where might be the culprit and I shown him the vacuum assembly.
At first sight he told me that he didn't like very much the black original connection at the end of the long pipe and just before the actuator assembly.
He took it off and replaced it with a new connection of his own, but without any guarantee to solve the problem.
On the way back, BINGO! My CC weakness was fixed and the CC as efficient as before.

He is an ace!

23rd March 2023, 06:50	#1
Dorchester2 incurable Rover addict Rover 75 Saloon V6 2.5 1999 - Rover 25 1.4 2002 - Rover 214i cab 1994 - Rover P5b coupe 1968 Join Date: Sep 2017 Location: Bioule. South West of France. Posts: 1,647 Thanks: 612 Thanked 385 Times in 223 Posts	Weak cruise control on an auto box KV6 Is there anyone here experiencing a weak CC on an auto KV6? Very recently I noticed that my cruise control was apparently working - light on switch, speed locked at the wheel then pedal automatically pressed - but it looks a bit hard to maintain the speed and slightly and slowly loosing speed. But if I do a long pull on the "set+" wheel control, the engine is once more able to accelerate by itself and I can release the button at the speed required. But progressively loosing speed again after a short while. I am now suspecting a leak in the vacuum pump. But I can't find any new from old stock as we say. All vacuum pumps available are used ones from Range Rover P38 same era and look similar as the one I may need but the plug which isn't the same. Your help would be greatly appreciated because suffering from sciatica since years, that cruise control is vital to put my legs at rest on a long trip. Thanks a lot. __________________ Rover 75 V6 2.5 Auto Connie born 1 July 1999, 24 kOhms resistor, 10 kOhms manual starter, full E85, modified airbox, full derestricted SS exhaust line, power & torque remap -> 202 bhp This vehicle was the 7,517th 75 to run off the production line, out of 112,381 This vehicle was the 1,190th 75 2.5 V6 Contemporary to be made out of 8,214 This vehicle was the 2,032nd 75 in Atlantic Blue Pearlescent (code: JEY) to be made out of 2,572 Atlantic Blue Pearlescent 75s

23rd March 2023, 13:27	#5
stocktake Vis Whiz Rover 75 2.5 auto Saloon Join Date: Jun 2007 Location: LEEDS Posts: 20,603 Thanks: 2,057 Thanked 3,056 Times in 1,621 Posts	Item three in your diagram is the vacuum assembly, it works on a vacuum being pulled. They can leak air or the pipe that connects to the unit develops tiny leak therefore slowly losing the vacuum. __________________ Dave... Lost a few stones and a Gall Bladder and part of a bile duct and all of my dignity in the suppository incident Last edited by stocktake; 23rd March 2023 at 16:44..

23rd March 2023, 14:07	#6
Dorchester2 incurable Rover addict Rover 75 Saloon V6 2.5 1999 - Rover 25 1.4 2002 - Rover 214i cab 1994 - Rover P5b coupe 1968 Join Date: Sep 2017 Location: Bioule. South West of France. Posts: 1,647 Thanks: 612 Thanked 385 Times in 223 Posts	Thank you buddie. Hence which of the two I've shown should be the culprit ? And how to cure the problem ? By a repair (which ? ) or a swap ? Thanks a lot. I'm so dumb I need to be sure. __________________ Rover 75 V6 2.5 Auto Connie born 1 July 1999, 24 kOhms resistor, 10 kOhms manual starter, full E85, modified airbox, full derestricted SS exhaust line, power & torque remap -> 202 bhp This vehicle was the 7,517th 75 to run off the production line, out of 112,381 This vehicle was the 1,190th 75 2.5 V6 Contemporary to be made out of 8,214 This vehicle was the 2,032nd 75 in Atlantic Blue Pearlescent (code: JEY) to be made out of 2,572 Atlantic Blue Pearlescent 75s

23rd March 2023, 16:51	#7
stocktake Vis Whiz Rover 75 2.5 auto Saloon Join Date: Jun 2007 Location: LEEDS Posts: 20,603 Thanks: 2,057 Thanked 3,056 Times in 1,621 Posts	https://rimmerbros.com/Item--i-GRID001952 Item 3 SCC100110L search by part number there may be cheaper sellers. There are no electrical connections on this part it simply holds a vacuum https://www.bing.com/images/search?v...t=0&ajaxserp=0 BUT FIRST: Check the push on pipe hasn't split/come loose, lot cheaper to replace. There are also 2nd hand throttle bodies on ebay including this part but it's not saving much https://www.ebay.co.uk/itm/393995464...kAAOSwGuViNzM0 __________________ Dave... Lost a few stones and a Gall Bladder and part of a bile duct and all of my dignity in the suppository incident Last edited by stocktake; 23rd March 2023 at 16:56..

23rd March 2023, 16:54	#8
Dorchester2 incurable Rover addict Rover 75 Saloon V6 2.5 1999 - Rover 25 1.4 2002 - Rover 214i cab 1994 - Rover P5b coupe 1968 Join Date: Sep 2017 Location: Bioule. South West of France. Posts: 1,647 Thanks: 612 Thanked 385 Times in 223 Posts	Thank you so much Dave. It's crystal clear. But there isn't a single "SCC100110" available on Ebay. Only Rimmer's... __________________ Rover 75 V6 2.5 Auto Connie born 1 July 1999, 24 kOhms resistor, 10 kOhms manual starter, full E85, modified airbox, full derestricted SS exhaust line, power & torque remap -> 202 bhp This vehicle was the 7,517th 75 to run off the production line, out of 112,381 This vehicle was the 1,190th 75 2.5 V6 Contemporary to be made out of 8,214 This vehicle was the 2,032nd 75 in Atlantic Blue Pearlescent (code: JEY) to be made out of 2,572 Atlantic Blue Pearlescent 75s Last edited by Dorchester2; 23rd March 2023 at 16:58..

23rd March 2023, 08:14	#2
dave lincs Posted a thing or two Rover 75 Saloon Join Date: Mar 2014 Location: Louth Posts: 1,450 Thanks: 380 Thanked 986 Times in 476 Posts	Check the vacuum unit on the throttle body I have had few of those leak

23rd March 2023, 08:35	#3
stocktake Vis Whiz Rover 75 2.5 auto Saloon Join Date: Jun 2007 Location: LEEDS Posts: 20,603 Thanks: 2,057 Thanked 3,056 Times in 1,621 Posts	Almost certainly what Dave diagnosed, the bellows or the push on pipe that connects to it. __________________ Dave... Lost a few stones and a Gall Bladder and part of a bile duct and all of my dignity in the suppository incident

24th March 2023, 09:20	#9
Dorchester2 incurable Rover addict Rover 75 Saloon V6 2.5 1999 - Rover 25 1.4 2002 - Rover 214i cab 1994 - Rover P5b coupe 1968 Join Date: Sep 2017 Location: Bioule. South West of France. Posts: 1,647 Thanks: 612 Thanked 385 Times in 223 Posts	I may have found the same one for a better price at Allbrits'. 50.19 € instead of 66.34 € at Rimmers'. And no import duties for us on the continent as they are located in Germany. I've just ordered and am waiting for their invoice. https://allbrit.de/xepc.cfm?PAGE=138...E=DE&CAR=SARRJ __________________ Rover 75 V6 2.5 Auto Connie born 1 July 1999, 24 kOhms resistor, 10 kOhms manual starter, full E85, modified airbox, full derestricted SS exhaust line, power & torque remap -> 202 bhp This vehicle was the 7,517th 75 to run off the production line, out of 112,381 This vehicle was the 1,190th 75 2.5 V6 Contemporary to be made out of 8,214 This vehicle was the 2,032nd 75 in Atlantic Blue Pearlescent (code: JEY) to be made out of 2,572 Atlantic Blue Pearlescent 75s

25th March 2023, 19:14	#10
Dorchester2 incurable Rover addict Rover 75 Saloon V6 2.5 1999 - Rover 25 1.4 2002 - Rover 214i cab 1994 - Rover P5b coupe 1968 Join Date: Sep 2017 Location: Bioule. South West of France. Posts: 1,647 Thanks: 612 Thanked 385 Times in 223 Posts	End of story... 1. Germans' knavish trick: Allbrits claimed that they had no more any SCC100110 for Rover 75 at 50€, but that they could provide me with SCC100110L for Land/Range Rover (and Rover 75 100% compatible!) at 76€!!! Easy: it's exactly the same item! Anyway I'd ordered one for peace of mind. 2. I came to my mechanic's this morning to cure my coil & plug problem (see my post https://www.the75andztclub.co.uk//fo...12&postcount=1). In the end I told him every little detail about my CC weakness. He asked where might be the culprit and I shown him the vacuum assembly. At first sight he told me that he didn't like very much the black original connection at the end of the long pipe and just before the actuator assembly. He took it off and replaced it with a new connection of his own, but without any guarantee to solve the problem. On the way back, BINGO! My CC weakness was fixed and the CC as efficient as before. He is an ace! __________________ Rover 75 V6 2.5 Auto Connie born 1 July 1999, 24 kOhms resistor, 10 kOhms manual starter, full E85, modified airbox, full derestricted SS exhaust line, power & torque remap -> 202 bhp This vehicle was the 7,517th 75 to run off the production line, out of 112,381 This vehicle was the 1,190th 75 2.5 V6 Contemporary to be made out of 8,214 This vehicle was the 2,032nd 75 in Atlantic Blue Pearlescent (code: JEY) to be made out of 2,572 Atlantic Blue Pearlescent 75s