190 hot start problem

[Paulmerc]

Hi everyone I have a 1989 190 2.0l petrol (pierburgh carbaurettor) model. The problem is the car won,t start when hot, My mechanic has changed the distributer and coil that did,nt help. Does any one have experience of this problem any help would be great . thanks for looking. Paul.

 

[AMGeed]

The common cause for hot start issues is the crank positions sensor (CPS)
On your engine you have a top dead centre sensor, indicated in the diagram below (Item 23) which does a similar job.
This sensor may well have failed but you need to have it diagnosed on Mercedes Star at a specialist if possible.
Try to avoid the main dealer due to high labour charges.

M 103.983 - T.D.C./POSITION SENDER-UNITS, IGNITION CABLE GUIDE & GROUND STRAP > Mercedes EPC Online > nemigaparts.com

Parts catalogs. Spare parts catalog Mercedes EPC Online. Mercedes. Car. Engine - Power Systems T.D.C./POSITION SENDER-UNITS, IGNITION CABLE GUIDE & GROUND STRAP.

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[Paulmerc]

The common cause for hot start issues is the crank positions sensor (CPS)
On your engine you have a top dead centre sensor, indicated in the diagram below (Item 23) which does a similar job.
This sensor may well have failed but you need to have it diagnosed on Mercedes Star at a specialist if possible.
Try to avoid the main dealer due to high labour charges.

M 103.983 - T.D.C./POSITION SENDER-UNITS, IGNITION CABLE GUIDE & GROUND STRAP > Mercedes EPC Online > nemigaparts.com

Parts catalogs. Spare parts catalog Mercedes EPC Online. Mercedes. Car. Engine - Power Systems T.D.C./POSITION SENDER-UNITS, IGNITION CABLE GUIDE & GROUND STRAP.

nemigaparts.com

Thanks for the reply, Thats the second time recently I,ve heard the crank sensor mentioned. I think i,ll just get this replaced and see if it works. Thanks again.
Paul.

 

[Bellow]

CPSs do fail with heat - but usually stop the engine when it tries to idle.
I'd look at carburation for this particular problem especially that the cold start fuel enrichment isn't being enabled. Removing a spark plug when the problem presents would confirm carburation if plug is wet with fuel but capable of spark (after drying plug if necessary). Lack of spark points to ignition - remembering these engines are notorious for damp within the distributor cap that mobilises with heat.
Odd, that the problem is hot start only - not stopping the engine or otherwise affecting its running.

 

[John N]

Hi everyone I have a 1989 190 2.0l petrol (pierburgh carbaurettor) model. The problem is the car won,t start when hot, My mechanic has changed the distributer and coil that did,nt help. Does any one have experience of this problem any help would be great . thanks for looking. Paul.

I'm assuming that your Distributor has a Capacitator some where Installed! (I have been away from Petrol Engines since the Early 80's) If so that may be the cause, the Capacitator Breaks down after getting Warmed up and won't Produce a Spark until Cooled Down!

 

[Bellow]

I'm assuming that your Distributor has a Capacitator some where Installed! (I have been away from Petrol Engines since the Early 80's) If so that may be the cause, the Capacitator Breaks down after getting Warmed up and won't Produce a Spark until Cooled Down!

Doubt that it has as external caps were for contact breaker systems. Anyway, as per failing CPS, a bad cap on a points system stops the engine.

 

[Paulmerc]

I'm assuming that your Distributor has a Capacitator some where Installed! (I have been away from Petrol Engines since the Early 80's) If so that may be the cause, the Capacitator Breaks down after getting Warmed up and won't Produce a Spark until Cooled Down!

Hi I am no mechanic but my mechanic changed the distributor with another one I supplied him which I bought second hand. This did not solve the problem. Thank you for the reply Paul.