1989 740GLE Bad Starting

[creeky740]

Hi all,

I have a problem with my old 740, it starts terribly! Not as many will think you have to crank it for ages, it goes almost straight away but not on all cylinders! The normal procedure is two perhaps three start and it shakes the whole car until the others join in. Once hot it runs and drives perfectly as well as pulling well through the gears.

It is fitted with a Bosch K jetronic system and is the 2.3L version. Fuel pump and relay have been replaced along with air flow meter and hall effect unit/distributor. Over the last few years nearly all the seals in the injection system have been replaced.

It is better than it was but the bad starting persists and keeps shaking the exhaust apart and given the fact the fit on pattern parts is usually awful this is not helping!

Ideas anyone?

Thanks

Jim

[NI_Volvo_Nut]

I'm not up on the names of the injection systems, but I think yours is the mechanical injection? If it is could be the cold start sensor, this packed up on my car, started perfectly when cold, but flooded itself when warm, I'm sure the sensor could cause the problems the other way about too, the snesor is located at the very rear of the manifold. I'm sure someone with a bit more knowledge will be along shortly to confirm a test procedure, I had a spare one, so I just replaced it and was lucky enough.

[Oilydad]

Not firing on all cylinders?

One of the plugs is defective.

One of the plug leads is defective.

Or possibly that the leads have been replaced wrongly, so the firing order is wrong? It WILL run like a pig.

Or that the ignition timing is not right?

Or that you have a fuel supply problem to one cylinder or a wiring loom break to one injector, or a duff injector?

Ideas......

[NI_Volvo_Nut]

But when it warms up it runs fine........

Possible headgasket, does it use water or oil?

[creeky740]

Hi all,

It does not use a drop of water or oil. The HT leads have been replaced as has the distributer as it had the standard fault where oil enters this causing non-starting. Timing belt has been done recently and the timing is spot on. Fuel pump and relay have been replaced this year and oil is changed reguarly.

I recently bought a battered 760 Turbo of the same age with a blown head gasket and that starts perfectly despite having been stood for 18 months!

The 740 has been to a specialist as the timing belt jumped 3 teeth causing it to run like a pig earlier in the year (hence why it was replaced for safety). The bad starting has been going on for years (have had the car for 18 years, 2nd owner 1st was Shell UK, I kid you not!) which is why almost all the rubber seals/pipes have been replaced as well as many other parts trying to cure the fault sometimes succeeding for a week then it reverts back to how it was.

As far as I know all the electrical connections are good with no sign of corrosion (those on the hall effect unit were spotless).

Whit it starts you can clearly hear the misfire before all cylinders join forces at sligtly higher revs. When you take your foot off the throttle it will tick over perfectly so it is unlikely to be anything to do with the idling control.

Over to the experts!

Thanks

Jim

['88740GL]

Have you checked your injector seals? Mine was idling weird when cold and jumping around for months until i found that the seals around the injectors were leaking air past them into the intake manifold, then it ran like crap, but was fine when it was warmed up.... Try some wd40 and with the straw spray it around the injector seats, and wiggle/lift up the injectors...if the wd40 is suddenly sucked in and the engine revs speed up/smooth out then theres your problem! try it on all 4....even if you find one leaky seal, replace them all!

Good luck!

[NI_Volvo_Nut]

What engine code is in your car, B230E or F?

[creeky740]

Hi,

Injector seals have been replaced as I had the same problem a while back and a recent check showed No1 was leaking again so they were done a second time with little noticeable difference to the running.

I will get back to you on the engine code, it is out and about at the moment!

Thanks

Jim

[redboy]

I have exactly the same problem with my 1979 Carburetted 245!
I've narrowed it down to the 'third cyl from the front' by taking off HT leads and seeing which one doesn't make a difference. If you take off a lead to a good cylinder, it will either run even worse or stall. If you find the bad one, it won't make a difference.

I think I have- and you might have- a very slight head gasket failure.
My hypothesis is as follows:
Essentially, the alloy head cools and heats faster than the iron block. When I shut off the engine, the head 'shrinks' as it cools. Over the past 31 years, the head gasket has lost its elasticity to seal properly, even though its probably not 'blown.' What this does, is let a very small amount of coolant into the cylinders overnight- enough to wet the spark plugs.

As the engine warms up, the spark plugs dry off, and with a cough, it sputters back into smooth running.

Now, I also use only very little coolant- 1/2 litre a month if that. I also don't have any residue in the oil or coolant.

I'm going to do my head gasket in the next month or so, and will post my pics on the 240 section.

cheers,
Brian

[creeky740]

Hi all,

The engine is a B230E. The head gasket has been checked and it is fine and it does not use a drop of water.

When it starts with the throttle in the right place all four cylinders fire right away but this is hit and miss get it wrong and it starts worse!

Thanks

Jim