Club 80-90 Forums

Ok, i'll try to keep this as brief and concise as possible!


This all started with a faulty idle stabilising unit on a trip to cornwall a few months ago. We finally diagnosed the problem (faulty idle stabilising unit) and got the van up and running, however it is quite significantly down on power. At the time we advanced the idle and fiddled with the dizzy a bit. We didn't touch the carbs.

Power is down at least 30 %. slower on acceleration, worse on hills and sat at 50 - 60 max ish with foot flat to the floor.Something is definitely not right. Originally I though we could have knocked the timing way out or something similar however, I had a mechanic (old VW specific) check the timing last week and it was only a couple of degrees out. It's now set correctly but there is only a mild improvement in the smoothness and power of the engine. He thought that, worst case scenario, the engine could be kaput but obviously wouldn't be able to know without doing a compression and leak test.

This one has me baffled because before the idle stabilising unit problem the engine was running really well. I know that they can sometimes just go but i'm hoping theres more to it than that. I was beginning to resign myself to saving up for a recon vege but then began to think the problem could be to do with the clutch. I'd really appreciate it if someone with more knowledge than me could advise whether a faulty clutch could cause these symptoms. I began to come to this conclusion when I got stuck turning round on a steep drive way - the damn van couldn't even back itself out and had to be towed! Particularly embarrassing because my saviour was Steve from Eastfalia! (i was picking up some bits)

The more I think about it the more it feels like the problem is t do with putting the power down, not a lack of power in the first place if that makes sense. I did have a new clutch fitted about 3 months ago and it was driving well but perhaps this has failed?

It's a 2ltr air cooled and carbs are in good condition and we checked that it is firing on all cylinders etc.

Any thoughts on insights most welcome!

Sam

i have the same problem with my 2.0 litre Aircooled cu,

its really slow picking up speed and it seems to hesitate if i put my foot down (especially in second gear) its like its bogging down with to much fuel, i think that it is the mixture as my carbs havnt been balanced properly since i have got it back on the road, also it is hard to get it going over 50mph and losses power up hills, once i get over 50 with the help of a slight downhill stretch it will hold at 55 - 60mph quite nicely,

i believe i just need to have my carbs set up properly and i think there is an air leak wich is also not helping,
not sure how i check for air leaks though?,

If your clutch is slipping you should notice it when pulling away or accelerating hard in low gears. Revs will increase but the van doesn't pull. It probably won't make much difference to your top-end speed on a flat road, you'll just take longer to get there.

When you got the timing checked was it done with a strobe at idle and at +3000 RPM? It really needs to be right at both ends of the rev range. Have you got a vacuum advance dizzie and are the idle stab and ECU the right ones for the van? A faulty Idle stab unit shouldn't cause you to lose power, a lot of T25's don't even have them connected. Are you sure it wasn't the ECU that failed and has been replaced with one off the wrong engine type?

My van is a standard 2ltr CU, with solex carbs and a 009 dizzie (idle stab & ECU disconnected) and it happily pulls over 75mph on the flat and will cope with most hills in 3rd at 40-50 mph.

is it possible that my clutch is only slipping in second gear??? all other gears feel fine but when puling away it struggles when im in second gear, once im in third its fine,

do you have a pic of the ecu and idle stab unit? were are they located i want to check if mine are plugged in and try unpluggin to see if it runs any better

my van is a standard cu engine and top speed is 55-60mph on a flat, it will do 40-50 up hill in 3rd though i guess thats the norm with theese engines,
it just hesitates/bogs down abit when accelerating in 2nd, my carbs havnt been set properly though so maybe thats all it needs? plus the exhaust is rusty as f**k

for the poster who was enquiring about how to check for air leaks -
a post by em from other days -

'As a newbie to these engines you can't start better than a full service, so that you know that everything is sound. Cap, rotor arm, leads and plugs, oil and oil filter. '

'As its Aircooled, the vacuum leads will be vital...if they have fallen off lumpy running will ensue! Chokes working properly? When the engine is running, spray all round the carbs and manifolds with wd40 - if revs pick up, you have an air leak.'

Also informative - this article from the wiki -

https://club8090.co.uk/wiki/Fu ... _Air_leaks

elmo makaroy wrote:my van is a standard cu engine and top speed is 55-60mph on a flat, it will do 40-50 up hill in 3rd though i guess thats the norm with theese engines,
it just hesitates/bogs down abit when accelerating in 2nd, my carbs havnt been set properly though so maybe thats all it needs? plus the exhaust is rusty as f**k

You should get them carbs sorted mate, mine is happy at 70 and that's on LPG

thanks for the post hijack elmo


BOXY, thanks for the reply.

BOXY wrote: When you got the timing checked was it done with a strobe at idle and at +3000 RPM? It really needs to be right at both ends of the rev range. Have you got a vacuum advance dizzie and are the idle stab and ECU the right ones for the van? A faulty Idle stab unit shouldn't cause you to lose power, a lot of T25's don't even have them connected. Are you sure it wasn't the ECU that failed and has been replaced with one off the wrong engine type?

My van is a standard 2ltr CU, with solex carbs and a 009 dizzie (idle stab & ECU disconnected) and it happily pulls over 75mph on the flat and will cope with most hills in 3rd at 40-50 mph.

As far as i know the timing was checked correctly but I cant be 100% sure. I did try without the idle stabilising unit and there was no improvement int he performance. dizzy s the same that's been on for a while so should be ok. Am really confused by this one.

My van too sat happily at 70 - 75 if i wanted it to before this problem.

How would you check that the clutch isnt slipping? Is there a fool proof test apart from driving it?

sorry for highjacking, i didnt mean to i thought i had the same problems,

i have had the van serviced, oil plugs dizzy cap ht leads spark plugs rotor arm changed, the carbs have been sorted by ear so it runs but could be better, the garage did recomend that i changed a couple of rubber elbows that were aparently gone, but im not sure wich ones, how many rubber elbows do i have and were are they??

sorry for highjacking, i didnt mean to i thought i had the same problems,

i have had the van serviced, oil plugs dizzy cap ht leads spark plugs rotor arm changed, the carbs have been sorted by ear so it runs but could be better, the garage did recomend that i changed a couple of rubber elbows that were aparently gone, but im not sure wich ones, how many rubber elbows do i have and were are they??

How would you check that the clutch isnt slipping? Is there a fool proof test apart from driving it?

You pull on the handbrake, put the van in third and gently release the clutch from standstill. If the clutch is ok the engine will stall, or if the handbrake is iffy you'll move forward. If the clutch is shot you'll be able to let the pedal fully up, the engine will keep running and you'll smell the last little bit of friction plate burning!

Elmo

do you have a pic of the ecu and idle stab unit? were are they located i want to check if mine are plugged in and try unpluggin to see if it runs any better

Have a look at the posting below, there's a photo showing the Idle stab & ecu. Don't disconnect the ecu because your engine won't run without it if you've got electronic igniton. The two plugs on the idle stab can be un-plugged from the unit the connected together.

viewtopic.php?f=37&t=78331

the garage did recomend that i changed a couple of rubber elbows that were aparently gone, but im not sure wich ones, how many rubber elbows do i have and were are they??

You'd be better off asking the garage, but they might have meant the one that connects the metal balance pipe to the left hand carb. If its leaking or missing then I'd be surprised if the engine would even idle.

BOXY wrote:

You pull on the handbrake, put the van in third and gently release the clutch from standstill. If the clutch is ok the engine will stall, or if the handbrake is iffy you'll move forward. If the clutch is shot you'll be able to let the pedal fully up, the engine will keep running and you'll smell the last little bit of friction plate burning!

cool. worth a try!

well, I tried putting it into 3rd, hand brake on and slowly lifted my foot off the clutch. When the pedal was fully released the van did stall but it ran up to that point. Basically i dont really know if it's slipping or not. Cant be too shot though because it did reach the stalling point

When you had a new clutch fitted did the garage say it would need re-adjusting once it had bedded in? The point where the clutch engages on your van sounds like its at the top end of the pedal travel. It might be that your clutch is slipping at higher revs but is still biting enough to stall the engine at idle. I'm sure someone here will be able to tell you how to adjust the bite point if the garage that fitted the clutch won't do it.