for the following specific problems.
A. The car engine is not running as perfect as when it was new. It runs poorly or is making
black clouds. The air-gas mixture is either too poor or too rich (fat). The engine may even be hard
to control with the pedal. The following does not apply for diesel engines.
B. Regarding elder vehicles and corrosion on contacts in electrical wiring: Change old fuses
that are made of corroding metal. They are not only corroding in their ends, so even if you get rid
of the corrosion at the ends, you may still suffer from a voltage drop.
- The engine has an ordinary carburator (non-fuel-injection). Check the air filter. If you
already have changed it, may be you changed to a filter that is too small for this engine. If f.ex.
the engine has got a camshaft with higher cams, the flow of air into the carburator will increase
and be more than what could be handled by the original air filter.
It happens that people change the spark plugs many times before the real problem is addressed. It
is so simple, that it many times is forgotten.
If the air filter is not an issue for solving this problem, the general solution is as follows:
As the perfect mixture is somewhere between too fat and too dry, you will have to get there,
by going from one extreme to the other.
First try, for about three seconds, to start the engine with full choke and no lifting of
the throttle. This did probably not start the engine, so now you should try starting the engine
with no choke and with full throttle. After some seconds, on the way to dry out, the engine will
encounter the optimal air-gas mixture. If the engine then does not start, check if plugs do
produce a reasonable strong spark. If not; you will have to enter another path, where some
advices further down might be to some help.
- The engine has a fuel injection system. Check all the connections
for the electrical wiring that is governing the injection. Oxidation is a problem on most parts of
metal. And on connecting ends, in electrical wiring, oxidation is annoying, especially if you are
struggling without finding out about the source for your problems.
One example: Mercedes Benz 190 E
(1986-1993) has, under the air filter, the air flow meter (where the air goes in) and a “centre” for the
injection. Mounted on its back side is an electrically governed injection regulator. It has 2 pins
for electrical contact. When they are corroded, they transfer wrong voltage, if any. Get rid of the
corrosion here and, if necessary, also on all other involved contacts from different sensors and
components. This worked for me. The black smoke and the jerking vanished. There are many instruction
videos on the internet that show in details how to fix different problems with the fuel distributor.
However; before going through to much troubles by dismantling this complicated part of the car,
first check the small black plastic rectangular shaped unit, about 4 x 8 cm, on the side of the
distributor. It has a three-pin electrical contact on it's outside. And it is attached by 4 screws
under plastic covers. This part is registering the position of the air flow meter by two stripes
of a carbon like matter. Therefore; Unscrew this part and check if these stripes are worned out.
If so, it is easy to replace this unit.
Another example: Some cars have the electrical
governing of the injection, mounted on/by the injectors. Check the electrical contacts there.
Important: If the engine, after it has reached working temperature, gets problems idling or running
on lower revs, and jerks when you try to accelerate, the injectors probably need to be cleaned.
Many of the additives in gas are unfortunately deposited in the injectors. This can easily removed
by a bottle of "Injector Cleaner", poured into the gastank. One 250 ml bottle, made by STP, mixed
with a almost full tank did the trick for me. Before the tank was run empty, the engine behaved
like it is supposed to.
- And finally, or rather; first of all: Check the ignition distributor, and then the spark
plugs. A spark plug cap may sometime cause a problem, and the cable to the spark plug may be
damaged. Even if the distributor would not let dirt or water inside, it may be worned out.
Note: Newer engines have one coil per spark plug, and therefore have no traditional
(high voltage) ignition distributor.
- If starting problems or black smoke persists, you will probably have to change the oil seals
around the valve stems. When theese seals are not worned, they tend to harden and most engines
will sooner or later need them replaced. This is an easy operation. Remove all plugs and
the valve cover. Make a simple special crow-bar-like tool, as follows; After the necessary dismantling
of the interior in the cylinder head, you will have both bolts and screw holes for attaching your
special tool with corresponding holes. Design its fork-like end so it can press down the spring around
a valve stem, in order to remove the split collets holding the valve. Replace the oil seal for one
cylinder at a time. And make sure, with a screw driver, that its piston is at the top during this
operation. A piston at its top position will prevent the valve from falling into the cylinder.
Compressed air in the cylinder is an alternativ, but nothing I would recommend, as the valve still
is pressedbinto the cylinder when trying to let it loose from the split collets. If you still
would be interested in filling a cylinder with compressed air, maybe in order to test the valves,
you may make use of an old and replaced spark plug. Just get rid of its inner parts and weld to
it a pipe that can be connected to a compressor.
C. When refilling brake fluid, after having shifted brake components, there will for
certain cars be necessary to fill the brake fluid up to the cap, not just to the "max level".
Otherwise you might be pumping nothing but air to the brake pistons.
This is a fact that is relevant for at least Mercedes 200E, W124.
D. When did you check the air filter to your lawn mower last time? Don’t
forget that the lawn mowers work in a very dusty environment.
E. Regarding the hot water and pressure tank Primus 8000.
This tank is used in trailors/mobile homes. If cracked by frosen water or by a water pressure that
has exceeded 2 bar pressure, the tank needs to be replaced. Getting this new tanks connection so
tight that it holds the pressure and water free from leaking is a challenge. I have noticed other people
asking about this on the internet, but there were no answers posted, until now. The sealing that
comes with this bottle-shaped tank is an o-shaped rubber ring to be placed on a "shelf" close to
the bottle's open end. However, this rubber ring is not thick enough to get in contact with the
the lid holding the water pipes. But changing to a thicker rubber ring is to no help in containing
water inside the bottle, when pressure is applied, unless a rubber quality for the sealing is found
that has the exact "softness". The solution, after a summer of trial and errors, came to be the
original rubber ring with rubber tape folded as a "U" over it, so that this rubber tape was
pressed under the sealing and above it. The combination of a harder inner and a softer outside was
what was needed. But this was not enough, as the threading for the bottles tightening screw consists
of round shaped threads. This caused the screw, when tightened, to slide over the threads and pop
the bottle open. To counter this I used a thick tape over mentioned threads.
In addition I secured the bottle with a strap, pressing it's ends towards each other.
Also check the water pressure, f.ex. by using the little tool for
checking air pressure in tires. If the water pressure is too high, it may be lowered by cutting
the length, of the electrical switch controlling spring, shorter.
Rolf Sjöström, 2021.