TheSamba.com :: View topic - You guessed it

Tue Nov 17, 2020 11:15 am

Hi Fam,

Have a 1983 air cooled FI (153K miles) named June. Recently replaced starter and ignition switch, and did valve adjustment.

Was running great for the past ~2K miles, now am having idle issues for the first time. Was on long drive after an hour going 20-60mph on highway, felt a slight lurching/slowdown every 10 seconds while sitting stopped in traffic. She stalled out right as I rolled into a parking lot to figure out what was going on. Then had trouble restarting - engine would crank/turnover, but wouldn't hold the idle for more than a second. Got her towed home, and now she starts/idles fine.

However, wanted to get her fixed before going on another road trip, which I'd like to do as soon as this week.

Read through several of the many idle issue posts on Samba, posting some pics of under the hood below.

Vacuum leaks - very possible - looks like original hoses on the vacuum advance, vacuum hose to the AAR, and the intake manifold. If i want to replace those, can I just take the existing vacuum advance and AAR hoses to an auto parts store and have them match the hose specs? Found the intake manifold sleeves online (https://www.gowesty.com/product/air-intake/24415/intake-manifold-hose?v=) but not those other hoses. Also, do you need to fully remove the intake manifold to replace? :shock:

Throttle - Noticed throttle does not "click" when I move it either forward or back. So I went to adjust the two screws on the bottom of the throttle body as directed by some videos (i.e. https://www.youtube.com/watch?v=eTphzNgG5ns&t=120s), but my throttle body seemingly doesn't have those screws (see pic below). The large flathead screw does work and adjust the idle when turning. Not sure which position is ideal though.

Air intake boot - checked, no cracks

Fuel pump and filter - look relatively new from PO. Fuel lines also newer than expected (I didn't replace)

Valve adjustment - recently did this, however, adjusted to TDC (0 degrees, straight up along seam). Did not read forum posts until after that, where it seems the valves can be set correctly anywhere from 25 degrees before or 5 degrees after TDC. Noticed that where I set the valves, the distributor for #1 was lined up exactly with the mark in the distributor. Also noticed afterwards that the plastic guard has timing marks on it (see pic below). Is that correct, and should I readjust to that notch as TDC? seems about how far off my distributor was to line up.

Long post (and long topic I know), thanks in advance for your guidance Sambaists!

Tue Nov 17, 2020 3:01 pm

Vcuum hose just needs to fit snuggly and not leak. Some of your pictures show poor looking old hoses. Replace as needed on yours.

The larger Intake Runner Hose/boots need to be leak free as well, if you can get the engine running again, spray Carb Cleaner or Brake Cleaner around those 4 intake boots on the runners while idling. If you have a cracked or loose boot, you'll hear the idle pick up from the extra fuel/spray getting into the vacuum of the intake on your running engine.
Remember that some cracks or leaks can be on the very bottom of the hose or boot, so not that visible while you're looking down on the engine.

I'll let someone else with Type 4 air cooled experience school you on checking the valves, there should be Hydraulic Lifters on your engine, so explaining preload and starting at dead 0 of adjustment before adjusting more is something that our experienced Samba members can add for you.

Tue Nov 17, 2020 3:19 pm

While I would agree that some of your hoses do look crusty, you don't mention a surging idle that would be indicative of a vacuum leak. I'm no expert on the t4 engine, but do know that the cold start injectors are problematic. If it's stuck open, that would make your idle rich and a possible "flooding" situation. There are a few members on this board who are good with the early air cooled engines. However, the bay window board has a lot more knowledge on that motor since it is basically the same as the last several years of bay window buses.

Good luck!

Hans

Wed Nov 18, 2020 4:04 pm

Question re throttle microswitch. It appears to never actuate. Two photo show throttle at idle and then held at full-throttle. This makes no sense to me. Is the actuator cam in perhaps wrong position? Motor would not start but while cranking and clicking the switch we got an easy start. Confused. Thanks as always for everyone's help ..

Wed Nov 18, 2020 4:14 pm

I don't have an air cooled throttle body to compare with. I can say that yours is pretty dirty and cruddy. How about spraying it down and cleaning it up. Maybe one of the spring actuated arms is jammed up and isn't able to rotate around and engage the switch...

Hans

Thu Nov 19, 2020 9:34 am

Does unplugging one or both wires from the switch make any difference?

Fri Nov 20, 2020 8:09 am

Kaisan wrote: Question re throttle microswitch. It appears to never actuate. Two photo show throttle at idle and then held at full-throttle. This makes no sense to me. Is the actuator cam in perhaps wrong position? Motor would not start but while cranking and clicking the switch we got an easy start. Confused. Thanks as always for everyone's help ..

Don't know the throttle set-up on your Air Cooled, but it 'looks' like you only have 1 switch, and it's a roller activated for Wide Open Throttle, and in your second picture the metal tab just doesn't reach the roller. But I would get a Bentley or have someone who knows the throttle set-up comment for all of us here....

2nd thing, is that just dirt or gunk on your intake boot in the second picture, or a crack in the rubber boot near where it clamps to the throttle housing.... I can't tell

Fri Nov 20, 2020 9:00 am

These setups are touchy about vacuum leaks and have lots of hoses and other rubber that need periodic replacement. Since oil and other crud tend to sit on the bottom of the hoses, they typically first rot out underneath where you can't easily see that they have failed. It is good practice to replace all the vacuum hoses and boots when you first buy a rig and then to inspect them annually from then on. The stock style elbows tend to not be reinforced so finding aftermarket ones that have reinforcement is a plus.

Fri Nov 20, 2020 9:36 am

If you're looking for reliable you need to change out all of those vacuum hoses. They are very old. You boot looks covered in oil and crud, it needs to be changed out too. These are items that are not lifelong, they need to be replaced from time to time. They are not expensive and require maintenance. You'll never have a long lasting, properly running rig unless you change out maintenance items. You'll always be chasing your tail.

Replace them and and the vacuum line to your distributor remove, clean and inspect that boot, put it all together fresh and clean and you'll be on your way to a vacuum leak free system as it is designed to be. Then you can move on to the switch.

Fri Nov 20, 2020 12:19 pm

Thanks for the replies all - some updates over last couple days -

Vacuum hoses - indeed did replace the hoses connected to the AAR, and vacuum advance. also sprayed the rest (i.e. intake manifold) with starter fluid to check for leaks and no change when sprayed. You're right may still be cracked underneath.

Throttle switch - @wildthings checked with voltmeter and it should be working properly. Also according to Bentley, for my rig (2.0L air cooled) that is a rich-related switch only engaged when at full throttle. So potentially unrelated to my stalling issues (see reproduced scenario below).

Also took for test drive yesterday to these results -

Started fine, and held idle in driveway without issue for 1-2 minutes. Then took on road, no issues for 5-10 minutes going 30-40 mph.

Decided to go further and faster. Another 10 minutes and going ~50 mph, I hit a red light. and can feel it stalling. Pull it into a parking lot and it dies. I then had to keep it gassed while in neutral (it's A/T) at all lights to get it home.

Seems as if it's not getting enough fuel when warm. This is also the exact scenario that led me to create this post a week ago. So was able to reprodue the problem.

Thinking maybe it's a sensor or something else fuel related. What do you all think?

Thanks as always -

Fri Nov 20, 2020 12:23 pm

Cracks in the S-boot may open up once the engine compartment gets nice and warm.