There's a lot going on there! I once remember being told that the only way to eat an elephant is one bite at a time! I can't help thinking that you've just got to be systematic. Service the engine, get it running as it should, sort the linkage. Servicing may involve a vacuum system overhaul but you'll find that during the process! It's easy to write, but at the end of the day we are dealing with bits of metal and plastic designed to run synchronously with each other until something breaks, wears or moves. If something is changed, and it makes a negative difference, change it back. It's laborious, but how else to diagnose this old stuff? Do you have the manuals?
The engine should easily and rapidly rev to 4500 in neutral. It sounds to me like it starts very rich then runs out of fuel, goes weak (revs increase) and stops. Is the fuel pump actually pumping? The engine probably has hydraulic cam followers - has the preload been checked? Have you done a compression test? I guess not because you need the throttles to be wide open. Are you sure your son hasn’t made some ‘adjustments’ that he hasn’t told you about?
Has the adjustment on the back end of the cranked rod to the carbs moved? This is where you set up the shift points. See the troubleshooting guide. If you disconnect it does the idle speed come back down to normal. If so that’s where the problem lies. Or maybe elsewhere down the linkage to pedal.
Did you check those elbows on the outside of the inlet manifold as I suggested a few days ago? If you've lost brake servo assistance, these are favourite and one might have even torn in two. Opening a big hole into the inlet manifold(s) play royal havoc with your engine running and power.
The auto box and its operation with cables and twisty rod are new to us and we are learning with your help thank you. I did check the cranked rod long spring at the carbs and that end seems ok with only a little play in the rod at the box. My son has done some work on the mechanical fuel pump and it was on my list today to check fuel delivery and the carb float bowls. when the engine stops it hunts and then dies quickly. Ran out of time so check next time. When I saw the fuel filter was black I reckoned the tank was probably full of rust and as there was no fuel filter when my son bought the van, I have to assume the rust has got to the carbs. My son has bought a new Meyle pump which we could fit at some stage. The good clean tank from the old van is ready for fitting to the new van along with all new fuel pipes and lines etc. That's another job. Re that cranked rod from carbs to box, I didn't know there was adjustment at the box end. Another job for next time is to replace the ATF and filter parts and replace the diff oil. And yes, I did check the vacuum elbows outside the carbs and my son fitted these new a few weeks ago as the old ones were perished he said. Anyone have ideas about the throttle cable pedal to box? Can it be adjusted to take out the slack?
RE the compression test, we could presumably still do the test as its done cranking the engine when not running and I could use the carbs balance bar to fully open the throttles manually as the pedal won't open them? Does that make sense? Also the hydraulic lifters are on our to do list. The tappets are very quiet with no rattles or loud tapping.
Hi @theBusmonkey thank you for hitting the nail on the head. I 100% agree with you that this tangle needs to be addressed system by system. Its not my van and I can only advise and do jobs of course. All of the issues I mentioned are within our capabilities but my son is getting frustrated with it and is now talking about paying various vw experts to sort it all out. My son has spent a lot of time and cash on bodywork, paint, interior, interior electrics, pop top and more, but the van is unusable and Spring is here. The van was bought as a non running project and has come a long way in the last 18 months and like the Golf mk2 we restored which took us 2 years and we helped my grandson to restore his Golf mk2 as his first car and that took 2 years, restorations take time and we have learned to expect the unexpected along the way.
Anyone familiar with the accelerator cable setup on auto box vans, its an 010/090 type box so same as on late bays. The T25 is an early 1980.
Soooo .... Having skimmed through this post my conclusion seems to be the pointers are there but you're not actually solving anything... Fuel delivery seems an issue but nothing has been sorted despite having a new pump at the ready. Lack of a fuel filter = dirt in the system , butterflies not opening fully and unevenly etc etc etc . It's all basic elimination of very simple problems and until you sort the basics you'll get nowhere sorting out the complicated auto gearbox linkages. Sounds like you've both had enough, as indeed the previous owner had and decided to sell .. Simply fitting the other engine and gearbox as originally planned seems a better option to get sonny-boy out and about... Sent from my SM-G960F using Tapatalk
Not spent any time with a auto but is it worth disconnecting all the auto linkages and just concentrate on getting the engine running properly for now. the experts will be along in a bit to say it’s a not possible
Apply patience and be methodical. Make a check list. Forget about auto box for now. Make the engine run right. If it had rust going into the carbs look in the float bowls. If they are full of crud, clean the carburettors. My £100 Morris Marina had so much rust in the float bowl, the float jammed down on it at 100mph on the M27 ( downhill past Rownhams services, 1985) and it emptied the tank over the exhaust over the next 5 miles.. Adding a fuel filter which has gone black may now be starving it of fuel once it has started.. so it starts rich because of bad adjustment then loses power .. If you disconnect the throttle from the engine then the engine does not "know" its an automatic. You can do compression tests even throttle closed it just takes longer to get air through the idle circuit. If you have an air leak like maybe the brake booster , then insisting on throttle opening for compression tests is irrelevant. Check for air leaks and fix. Balance the carburettors, set the idle . Make the engine run right. Then fix that linkage.
That sounds like it is running out of fuel to me. Clean the carbs, check the fuel supply, if necessary, dump the fuel from the tank, replace the filter and use fresh fuel. And bear in mind a new pump may not work well or for very long. As has been said several times, get the engine running properly before moving on to the transmission. Yes, that’s how it should be done; plugs out and a fully charged battery of course. They should be quiet but because there is never any clearance the cam and followers wear quicker than a solid cam (allowing the engine to idle for long periods increases the wear). Note how far the valves open when you check the preload. It’s difficult to know what you are actually doing but it seems you are jumping from one thing to another hoping to solve a problem when you don’t really know what the problem is.
Apparently you can get a kit for throttle cable repair @mgbman tho I’ve not checked if that’s true yet. My van seems to be running better but as has been said already a list of things to do one at a time so that they can be discounted is the way to go. I’m still trying to persuade my mechanics that this is the sensible and logical option ps why are you under the van and your son in it!! Shouldn’t you get the comfy job?
the throttle cable from the pedal should pull the arm on the gearbox as far as it can go forward, that is in to the kickdown mode. disconnect the linkage arm to the carb first. From what you say if thats not hardly moving then that is the problem or part of the problem.
If the butterflies, on the carbs are hardly opening then it ain't going nowhere fast. adjust throttle cable first then rod to carbs, the butterflies should be wide open at full throttle. You may have other issues with mixture etc but its not going to make it that slow
Thanks for the helpful replies. I think my son is losing enthusiasm and he has a busy life. I am retired with time to work on it but the van is not on my driveway. My son is looking to sell the old van and his idea is to sell the parts, remove the glass, keep the engine and gearbox and send the shell for scrap. I am different, I think the old van would make a good cheap project for someone who is willing to do some welding and if it were mine I would put the parts back in the van and clear out the garage, leave the engine/gearbox in the van and sell it as a whole. What my son wants is to fix and use his new van and to me messing about with the old one is a waste of time and clouds the real objective. We don't really need the old engine and anyway the garage is already full and what time will my son have to work on it, it would probably just sit there. If it were me, I would sell the old van at a cheap price like £1000 to £1500 and let someone else restore and enjoy it. With all that out of the way, we could focus on sorting out the new van's running issues and get the driveway back and put the restored Golf mk2 back in the garage, Does that make sense?
Those carbs are great when in good condition. One torn elbow or connector and they fall on their face. It’s kind of all been said. Getting one going is quite a learning curve and with a neglected bus it’s usually a whole lot of little things. Nothing wrong with saying this is just not for me.
