Hello,

After changing the spark plugs my R11 runs a lot better, but still it does not run very steadily when idle. When waiting in front of a traffic light, the steering wheel/gearstick/the dashboard is shaking.

Therefore, yesterday I renewed the air hoses: the hose from the exhaust manifold (warm air inlet) was not tight around the exhaust. The cold air inlet hose had a big hole in it and was worn. I placed two flexible aluminium hoses; so the air intake is no problem anymore.

It didn't help.. the fuel filter is new, air filter is clean, spark plugs are new, spark wiring is OK, rotor (under the distributor) is new, distributor looks OK.

So today I pulled off the air filter housing to take a look at the carburettor. I pulled out the rubber seal between the air filter house and the carb, and it is worn around the holes for the screws. I don't think this seal can stop air from flowing in or out. Now I wonder if this could be a cause for running rough when idle?

Another possible problem: Haynes manual (chapter 'ignition') that the rpm should decrease when unmounting the vacuum hose from the ignition 'computer' (my car has the electronic ignition module). So I first increased the rpm (by pulling the choke) and disconnected the hose: no difference. Then I reconnected the air hose, disconnected the other side (on the carb.) and sucked on that side; again, no difference in rpm. Does this indicate anything? Is my ignition computer bad? Or should I increase the rpm by pressing the accelerate pedal instead of using the choke?

O, some data about the car: R11TL '87, C2J (1397 cc), Weber carb.

Thanks in advance, greetings,
Maarten Boersma

ga kleppen stellen (i dont know how this is called in english) this could be the trick

Oke, zaterdag maar eens naar kijken. Stond inderdaad ergens op m'n te-doen-als-niks-meer-helpt-lijstje. Moet ik dan een nieuwe pakking onder het kleppendeksel monteren of kan ik de ouwe nog wel gebruiken als ie er nog goed uitziet?

translation:
I'll take a look at the valve play saturday. It was indeed on my to-do-list when nothing else solves the problem. Do I need a new seal between the valve head and the cylinder head or can I still use the old one if it looks OK?

I used the old one last time after "shor visual inspection", and it was OK. You'd have to check if for oil leaks quite often, though.

Hello,

Thanks for the info; I did the valve adjustment, the play was in general 0,05 mm too wide (0,25 mm instead of 0,20 mm and 0,20 instead of 0,15 mm). I mounted a new seal as well (only EUR 4) , and replaced the carburettor seal, because it had holes in it.

Unfortunately, the engine doesn't still run any better. Now, a friend of mine looked at the engine, and noticed a 'black stripe' (maybe a hole?) between the upper and lower part (on the left side) of the inlet manifold. Maybe the metal has expanded/shrinked and caused a air leak in the inlet manifold. How can I easily check if the inlet manifold is leak? Putting a drop of water on the suspect spot and see if there appear bubbles? There is no petrol smell in the engine bay. The engine has had a short time of running hot, when there was a leaking heater matrix.

Haynes tells me that false air in the inlet manifold is a possible cause for a rough idle.. so I have a new point to focus on.

What is a reasonable price on a scrapyard for a inlet manifold? Are the same manifolds used on the F2N engine (I have the 1.4 C2J)? Can I use a manifold of a Volvo 340?

Thanks,
Maarten Boersma

...worn carburettor butterfly spindles. However, this isn't very usual on R11 Webers, as there are seals made of nylon around the spindle.

If you have separate inlet and exhaust manifolds (aluminum inlet / cast iron exhaust) then it can very well be a leaking manifold gasket.

If the manifold is in one piece and made of cast iron then another possibility, besides a leaking gasket, is a crack in the manifold. This is very common on C1J engines with all-cast iron manifolds.


Another thing that comes to mind is that the overheating has caused some part to warp. Either the inlet manifold sealing flange. Or even the cylinder head, letting pressure escape from combustion chambers.

***

Unfortunately you can't use manifolds from an F2N or a Volvo 340 engine. The 340 cylinder head is basically the same, but the engine is tilted 12 degrees backwards in the 11 whereas in the 340 it sits upright. So even if the manifold would physically fit, your carburettor would be tilted and wouldn't function correctly.

Zet de eerste cilinder in het bovenste dode punt einde compressieslag.(cilinder bij vliegwiel is de eerste).Stel nu de kleppen van de 4 cilinder.Draai de motor verder tot de kleppen van de 3 cilinder op tuimelen staan en regel de kleppen van de 2 cilinder,draai terug de motor verder zodaat de kleppen van de 4 cilinder op tuimelen staan en regel de kleppen van de eerste cilinder,draai tenslotte de motor verder tot de kleppen van de 2 cilinder op tuimelen staan en regel de kleppen van de derde cilinder.(tuimelen wil zeggen uitlaat klep en inlaat klep die op het moment van openen en sluiten staan)

If nothing else helps, try to increase fuel dosing, with a screw located behind the air filter box. It's visible between the filter box and the rear wall of the engine bay. Start the engine and let it idling. Rotate the screw to the left and watch the engine's behaviour - if it starts to work smoother - then reduce the fuel dose to "minimal effective one". If it does'nt - try to rotate the screw in opposite direction. It's better to check the exhaust gases after regulation, or to adjust the fuel dose under control of exhaust monitor, this will spare you suprises at the MOT. If you don't have access to the exhaust monitor - simply watch your spark plugs after you ajust the carb - if the electodes are totally black, the fuel dose is too high, and you'll probably fail the MOT, if the spark plugs are OK, then you should pass it with very little trobule.

Tell me if you've checked the procedure I've decscribed, and if it worked with your engine. It worked in my car.

PS WHEN ROTATING THE FUEL DOSING SCREW - REMEMBER TO COUNT THE NUMBER OF ROTATIONS YOU DO! IF SOMETHING GOES WRONG - YOU CAN ALWAYS RETURN TO THE INITIAL POSITION.

Artur

My parents' R19 suffered from a rough idle and hesitating/cutting out under light throttle or letting the car roll with gear engaged without depressing the gas pedal.

This was driving me nuts as nothing seemed to help. Everything seemed to be OK: the plugs, filters renewed, carb had been cleaned etc. The car had failed its previous MOT due to too high an HC level (over 800 ppm, allowed is 600 ppm) and had a cylinder head job to cure that. The workshop that did the 'head job' also took it to an MOT recheck, so I had no idea of the mixture other than that it was obviously within the levels required by law. Naturally I expected them to have adjustd the CO level to factory recommendations (1.5% +- 0.5%).
When I took the car to its this year's MOT (last Friday), I was somewhat shocked to see the emission readings. Sure, they were within the regulations all right, but the CO level was 0.26%!!! So the mixture was excessively weak. No wonder the idle was rough and there was lack of power. I'm just glad it hadn't burned a valve or a piston! The last time I take my car to that workshop again (they messed up the job otherwise, too)...
Well, as an immediate precaution I opened the idle screw quarter of a turn and, as if by magic, the rough idle/hesitating was almost completely gone. Naturally I've no idea if that 1/4 of a turn was too much or too little, so I'll have to go to another garage to have the mixture checked with a gas analyser.

BTW, here are the emission test results for the 19 (at idle):
CO: 0.26% (allowed 3.50%)
HC: 200ppm (allowed 600ppm)
CO2: 14.00%
02: 1.00% (allowed 5.00%)