Tickover in park

[amazon69]

Hello,

School me again please...when I put my W111 into Park, the tickover rises from the level it was at, regardless of whether it was in reverse or drive. Not a massive rise, maybe 100-200 rpm. Is that normal or does it suggest a vacuum leak somewhere for example? It's not presenting a problem, I'm just intrigued.

Thanks all.

Dave

[Frank Reiner]

Originally Posted by amazon69

Hello,

School me again please...when I put my W111 into Park, the tickover rises from the level it was at, regardless of whether it was in reverse or drive. Not a massive rise, maybe 100-200 rpm. Is that normal or does it suggest a vacuum leak somewhere for example? It's not presenting a problem, I'm just intrigued.

Thanks all.

Dave

Entirely normal; in neutral (& Park) the turbine in the fluid clutch is released and is turning at the same speed as the impeller. In a driving position the turbine is stopped when the vehicle is stopped, and hence presents a drag on the engine via the impeller.

[amazon69]

Great stuff, thanks Frank.

d

[97 SL320]

Generally normal however, if the idle is rough in gear and out of gear is higher than spec, the engine will need some attention. Usually this points to a lean condition.

Also for general info, when driving the car, it is OK to leave it in gear when stopped for a light / stop sign. Shifting to neutral then drive at every stop just causes more shifer and clutch plate wear.

Be sure to use the parking brake when leaving the car. " Park " position on an automatic transmission is a secondary car holding mechanism, the parking brake is the primary car holding mechanism.

It takes a decent amount of force to pull a transmission out of park when car cars weight is against park. This leads to shifter wear and the possibility of the shifter being in park but not the transmission.

[amazon69]

Thanks. I'm pretty sure the car isn't running lean..I've had a co2 meter on it, and all is good. It's a little rich if anything, certainly at idle, although only by a percentage point or so. It does tick over a little roughly however, I imagine that is down to a need for fresh inlet manifold gaskets and plenum seals, ( I replaced all injector seals) but that is a question for another post. Once off idle it is as smooth as you like with great power and immediate pick up, so I don't think there's much wrong there.
I don't move the lever around when at a light etc, and I do use the parking brake when I leave the car, although I can't say I'm a fan of the Mercedes handbrake physically.

[vwnate1]

So what, about 2% CO ? .

What's the HC level ? . under 500PPM I hope .

[amazon69]

Blimey..2% is a bit optimistic..it's at 4.5. I can't measure the HC level with my
device.

[Benz Dr.]

I think you'll find 4.5 % to be around the normal level.

[vwnate1]

Sorry .

When I did smog testing in the 1980's 2% C.O. was the baseline, the HC they wanted less than 500PPM and most of the older beaters than came in ran North of 700PPM......

These were all 4 cylinder engines .

[Diseasel300]

Originally Posted by vwnate1

When I did smog testing in the 1980's 2% C.O. was the baseline, the HC they wanted less than 500PPM and most of the older beaters than came in ran North of 700PPM......

Maybe for an emissions-equipped Cali-Car that's expected. Not really apples-to-apples comparison for a Euro (non-emissions) W111 from the 60s.

[vwnate1]

Just so ~ .

What I learned to do was make sure the ignition system was as good as it could get then tweak the carby as I watched the sniffer, tweak the CO down until the HC began to rise, and stop when I got the HC was low as it'd get , screw the CO.

This way the cars started fine and ran *much* better to boot, idled O.K. and didn't diesel when shut off hot, etc., etc.
.

[Idle]

Originally Posted by amazon69

Thanks. I'm pretty sure the car isn't running lean..I've had a co2 meter on it, and all is good. It's a little rich if anything, certainly at idle, although only by a percentage point or so. It does tick over a little roughly however, I imagine that is down to a need for fresh inlet manifold gaskets and plenum seals, ( I replaced all injector seals) but that is a question for another post. Once off idle it is as smooth as you like with great power and immediate pick up, so I don't think there's much wrong there.
I don't move the lever around when at a light etc, and I do use the parking brake when I leave the car, although I can't say I'm a fan of the Mercedes handbrake physically.

Two easy things to check for if the idle is rough and under power the engine is smooth.

One: Check the ignition points/timing. Use a dwell meter. Just a bit of wear in this area can cause what you are talking about. And just a quick peek at the points can tell you their condition.

I have seen engines where the contact point material was totally gone; all that was left was two tiny metal stalks. This was on a 1966 Dodge Dart. But the engine still ran. Poorly.

Two: Check your engine mounts. When they start to go the idle will seem rough but only because the engine is not mounted as solidly as it once was. Just start the engine, have someone step on the gas while you watch the engine. If the engine shifts slightly and then sounds smooth you know you have a busted motor mount. Plan on replacing all of them, including the transmission mount at the same time. If one is bad then the others are on the verge of death.

[vwnate1]

? I'm guessing no one has the old points wear meter any more ? .

Or, just use the VOM set to 10 VDC and see how much current is by passing the points when they're closed..... shouldn't be more than .01 V .

[amazon69]

Thanks for the replies, as ever. The car has Pertronix fitted, and the timing is bang on, so I don't think either of those are affecting the lumpy idle. I think it's vacuum leaks from the inlet seal things, which I am trying to sort.
Good call on the engine and 'box mounts though..they are next on my list. I am sure they will help reduce the feelings induced by the lumpy idle, but it is definitely not quite right. I like the idea of disguising the idle by smoothing out the mounts and engine shocks, but I like the idea of a smooth idle even more...I need to hunt down those 8 inlet manifold/plenum(?) seal things.

[vwnate1]

? Is this car fitted with Bosch D-Jetronic F.I. or carbies ? .

If F.I., VW typ III's and some Porsche/VW 914's used the same injectors making the to rubber seals per injector easy to find and cheap to boot .