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Has anyone experienced this symptom? See other threads by this ID in the Forums > Mercedes-Benz Sedans > S-Class (W140) for full version of what is going on.
Basically once the car warms up to operating temperature it stalls and is hard to restart. Works fine from cold. New radiator cap, thermostat and rad flushed has already been applied. Check engine light was already on. There is a connection stuck open that prevents use of a code reader. This was already a problem prior to over heating / hose fitting failure adventure.
Just looking for potential sources. Gasket failure already on the table as a possible cause.
Has anyone experienced this symptom? See other threads by this ID in the Forums > Mercedes-Benz Sedans > S-Class (W140) for full version of what is going on.
Basically once the car warms up to operating temperature it stalls and is hard to restart. Works fine from cold. New radiator cap, thermostat and rad flushed has already been applied. Check engine light was already on. There is a connection stuck open that prevents use of a code reader. This was already a problem prior to over heating / hose fitting failure adventure.
Just looking for potential sources. Gasket failure already on the table as a possible cause.
Reply here or in original thread.
99% chance this is caused by low fuel pressure.
BTW. lean mixture is exactly known to cause high heat... the root of your head gasket failure.
Last edited by CaliBenzDriver; Sep 22, 2025 at 06:21 PM.
Will talk to my neighbor about these possibilities. He is a retired mechanic who collects old cars as well. Might be as simple as a clogged filter. Will see if he has a way to measure fuel pressure.
Will talk to my neighbor about these possibilities. He is a retired mechanic who collects old cars as well. Might be as simple as a clogged filter. Will see if he has a way to measure fuel pressure.
Won't be surprised if it is multiple problems.
Yes, exactly!
Chances are it is a combination of issues centered around fuel delivery.
Once low fuel pressure is validated, research what is causing it ( pump, filter, regulator, low voltage, ...)
Has anyone experienced this symptom? See other threads by this ID in the Forums > Mercedes-Benz Sedans > S-Class (W140) for full version of what is going on.
Basically once the car warms up to operating temperature it stalls and is hard to restart. Works fine from cold. New radiator cap, thermostat and rad flushed has already been applied. Check engine light was already on. There is a connection stuck open that prevents use of a code reader. This was already a problem prior to over heating / hose fitting failure adventure.
Just looking for potential sources. Gasket failure already on the table as a possible cause.
Reply here or in original thread.
A failing crankshaft position sensor is the most common cause for a W140 to stall when hot. It's a known issue. Try replacing that first before considering a major repair like a head gasket.
Could a failing crankshaft position sensor have been the cause of the initial overheating/failed coolant connector?
Long story is in the W140 forum but basically the car overheated/blew a coolant part within 20 minutes of it starting one day (running at highway speed/RPM). Had worked without any temperature issues for the first 5,000 kilometers I drove it. Is very low kilometers for age (<150K) but had been sitting. Didn't do anything to engine other than change oil.
Could a failing crankshaft position sensor have been the cause of the initial overheating/failed coolant connector?
Long story is in the W140 forum but basically the car overheated/blew a coolant part within 20 minutes of it starting one day (running at highway speed/RPM). Had worked without any temperature issues for the first 5,000 kilometers I drove it. Is very low kilometers for age (<150K) but had been sitting. Didn't do anything to engine other than change oil.
VIP Crank sensor would set a hard FAULT CODE and shut off suddenly unlike weak fuel pressure...
Try to prioritize diagnosis over swapping lucky parts and diagnosing afterwards.
Consider getting your old THERMOSTAT replaced and the radiator hot-side hose.
This will help renew most of the coolant mix.
Keep a close watch on engine temperature while this is known issue.
> Loose belt over bad water pump can help prevent proper coolant flow.
> MAYO... TERMINAL FAILURE :
During extreme pressure events, Mercedes engines can mix coolant and engine oil through heat exchanger timing covers seals to relief pressure.
Pay close attention to oil + coolant not creating a MAYO mix.
Last edited by CaliBenzDriver; Sep 26, 2025 at 08:38 PM.
Thermostat replacement was done after initial blown hose. Coolant flow seems normal (running with the cap off shows circulation). No sign of oil in coolant or coolant in oil.
My mechanic indicated that the coolant was circulating properly.
A user in the other thread speculated it may be a Mass Air Flow sensor problem. These are very expensive where as the crankshaft position sensor is relatively cheap. How difficult is it to replace a crankshaft position sensor? I understand your point about just swapping parts. I have limited diagnostic abilities. I bought a code reader (pulse counter) over the internet but the lights are stuck on (a circuit fault in the system) and it will not flash codes. Have found a specialty garage in the city that I am thinking of flat bedding the car to for professional repair.
Thermostat replacement was done after initial blown hose. Coolant flow seems normal (running with the cap off shows circulation). No sign of oil in coolant or coolant in oil.
My mechanic indicated that the coolant was circulating properly.
A user in the other thread speculated it may be a Mass Air Flow sensor problem. These are very expensive where as the crankshaft position sensor is relatively cheap. How difficult is it to replace a crankshaft position sensor? I understand your point about just swapping parts. I have limited diagnostic abilities. I bought a code reader (pulse counter) over the internet but the lights are stuck on (a circuit fault in the system) and it will not flash codes. Have found a specialty garage in the city that I am thinking of flat bedding the car to for professional repair.
Thats all good report... going forward then
You need a Mercedes specialist not any generic shop. They will have the MB specific tool to read your chassis and understand what to do instead of swapping the most expensive parts.
Your '95 car is not OBDII compliant, it requires MB 38-pins access tool.
Troubleshooting computers is not a parts lotery. Absolutely zero need to guess when the ECU is already measuring everything.
A great many parts can cause your stalling yet only one is causing this.
ECU data will help sort things out: money well spent!
Last edited by CaliBenzDriver; Sep 27, 2025 at 04:34 PM.
i had same problem and changed a bunch of parts but figured mines out and it should have been the first thing i checked. Distributor caps and rotors solved my headache and it was the easiest thing to check by removing a few screws
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