88 300E A whole lot of cranking! - PeachParts Mercedes-Benz Forum

johnflight1 · #1 04-04-2010, 06:52 AM

88 W124 3.0. As time goes by it takes more and more cranking to start the car. It always starts but takes about 10 sec of cranking.It seams to be taking longer as the months go on. It is worse when cold.not as bad when hot,but not perfect then either.
NEW PARTS....
OVP--Helped idle
1Fuel pump----It was noisey.
Aux Fan----It Died
Nothing else related to eng.

Cal Learner · #2 04-04-2010, 07:25 AM

Well, from your list of repairs made and without knowing the maintenance history of the car, the obvious suggestion is a tuneup: plugs, wires, cap/rotor, air and fuel filters. After that, fuel pressure/volume testing to see what's going on with the fuel system.

Gilly · #3 04-04-2010, 08:10 AM

Nope, it's the valve stem seals. Guaranteed.

Gilly

mespe · #4 04-04-2010, 01:07 PM

Sound like maybe CSV

johnflight1 · #5 04-04-2010, 09:16 PM

Hi Gilly, I have changed the valve stem seals about 13 years ago it has not burned oil since. When I changed them I also put new seals and gaskets on the front cam cover under the dist and new valve cover gaskets. I was about to change the front cover seals again since they are leaking again.
And the car probably is due for a tune up!
NO smoke out exaust. , But I am interested in the valve stem seal theory? is it sucking air leaning out the mixture? Thanx John

johnflight1 · #6 04-04-2010, 09:18 PM

Hi Mespe, What is CSV? Thanx John

ps2cho · #7 04-04-2010, 09:26 PM

Cold Start Valve. Could be leaking fuel.

johnflight1 · #8 04-04-2010, 09:52 PM

Thanx Ps2cho, That sounds easy. How about injectors? I heard somthing about leak back or leaking injectors is that possible.

johnathan1 · #9 04-04-2010, 10:38 PM

This always happens to M103's. Replace the spark plugs.

ps2cho · #10 04-04-2010, 10:57 PM

Well before replacing them...first just make sure there are no deposits and they are gapped correctly.

Gilly · #11 04-04-2010, 11:08 PM

In 13 yrs the valve stem seals have hardened. Diagnosis would be confirmed by yellowish deposits on the spark plug, especially the insulators.
Gilly

pawoSD · #12 04-04-2010, 11:45 PM

I enjoy reading these diagnosis threads.....everyone has a different thing it could be....personally my 300E has the same issue....it likes to crank before starting.

The following has been replaced on my car so far:

-valve stem seals, uses 0 oil now between changes
-spark plugs
-wires
-rotor/cap
-fuel pump check valves
-injectors
-injector holders/seals
-fuel filter
-OVP
-coil
-Cold start valve has been tested, does not appear to leak
-engine temp sensor
-intake air temp sensor
-crank position sensor

Yeah, and it still does it, especially when hot and having sat turned off for 15-30 minutes.

Tomorrow I am having the dealer test the fuel pressure and duty cycle on the engine to see if they are in spec. Thing is, once it starts, it runs perfect....and gets 20-23mpg every tank.

ps2cho · #13 04-05-2010, 01:31 AM

One thing I have noticed is that the EHA does in fact make a difference on start quality -- Whether that be the EHA, or simply it's influence on the mixture, I am not sure...

All I know is that when I swapped the EHA from my 260E (which used to bog down and flood when you gave it a heavy foot) into my 300TE (which was running fine other than a low MPG) I noticed MPG improvements on the 300TE (14mpg av to 16mpg avg) and the 260E no longer bogged under acceleration.

Go figure

.

--

That and after I broke my coolant temp sensor (accidently) I noticed right away that starting took longer. As soon as I replaced the sensor it returned to normal. That is a 100% accurate observation as I double tested it and could repeat the same condition after it was unplugged. So you may want to check it is functioning. I think since yours is an 88 it has the 4 pin "plug" sensor instead of the two prong sensor that is prone to break easily.

johnathan1 · #14 04-05-2010, 02:02 AM

Quote:

Originally Posted by pawoSD

I enjoy reading these diagnosis threads.....everyone has a different thing it could be....personally my 300E has the same issue....it likes to crank before starting.

The following has been replaced on my car so far:

-valve stem seals, uses 0 oil now between changes
-spark plugs
-wires
-rotor/cap
-fuel pump check valves
-injectors
-injector holders/seals
-fuel filter
-OVP
-coil
-Cold start valve has been tested, does not appear to leak
-engine temp sensor
-intake air temp sensor
-crank position sensor

Yeah, and it still does it, especially when hot and having sat turned off for 15-30 minutes.

Tomorrow I am having the dealer test the fuel pressure and duty cycle on the engine to see if they are in spec. Thing is, once it starts, it runs perfect....and gets 20-23mpg every tank.

I used to have a similar problem with my inline-6 Toyota. I replaced everything, and it still would crank and stumble when hot. I was told that it was caused by "heat soak".

Also, a bad sensor seems like a likely cause. The ECU needs to know when the engine is cold so that it can inject more fuel (open the CSV) and if the temp sensor is bad, then it has no way of knowing.

johnflight1 · #15 04-05-2010, 04:10 AM

yea I guess my valve stem seals are due it has been 14 years! but still no smoke on start? I will check the plugs for yellow deposits they are due also anyway. I am also going to replace the sensor on the head mine is a 2 prong.
it is the last one on the back of the head that tells the fuel inj syst the eng temp. I like what one of the guys said about the bog or dead spot with a heavy foot. I also have this symptom. makes alot of sense. I will order one of those also. I have been neglecting this poor car since I got my 96 SL500. That thing is a handfull with the ASR ABS lights on,but thats a whole other post. Thanx John .I will update when parts are rpl...........................