240 GLT saloon restoration project

[Juular]

It lives! Will post a video and photos layer. However I do have a couple of snags.

I cleaned the distributor and all ignition connections. I changed the spark plugs, cleaned and tested the cold start injector, tested the cold start air valve, and checked the metering plunger was free.

Started first turn of the key, but wouldn't run without throttle.

Adjusted the baseline idle adjustment (the black plastic thumbscrew on the throttle) and now it idles between 700 and 900 without stalling. It also revs beautifully and sounds perfect. However I have the following issues.

- cold idle is very rough, whole car shakes.

- It smells very rich.

- engine seems to bog right down when given a small amount of throttle. Larger amounts are fine.

Once it warms up, idle is significantly improved. Still smells rich though.

It's a k-jet, no idle air control valve, no idle microswitch.

Not sure what to look at next. Idle mixture screw? It appears to be hidden under a long tube that means an Allen key doesn't actually reach it.

Thermotime switch? Where is this located anyway - does it go into the coolant jacket?

Very happy to have it running, but I think it may be tricky to drive in its current state.

[Laird Scooby]

If memory serves you'll need a long 3mm Allen key for the misture screw. A quick test of the thermotime switch would be to unplug the electrical connector from the cold start injector once the engine is running, if it smells less rich and the idle smoothes out then suspect the thermotime switch.

Something in the back of my mind says the thermotime switch is on the back end of the left hand side of the head, under the inlet manifold. Might be wrong though.

[Juular]

Originally Posted by Laird Scooby

If memory serves you'll need a long 3mm Allen key for the misture screw. A quick test of the thermotime switch would be to unplug the electrical connector from the cold start injector once the engine is running, if it smells less rich and the idle smoothes out then suspect the thermotime switch.

Something in the back of my mind says the thermotime switch is on the back end of the left hand side of the head, under the inlet manifold. Might be wrong though.

Excellent, thank you.

The more I read, I am thinking the cold start injector shouldn't be running at all currently? It's around 3-5C here.

I have dug out some Allen keys and will adjust the mixture tomorrow.

[Laird Scooby]

Originally Posted by Juular

Excellent, thank you.

The more I read, I am thinking the cold start injector shouldn't be running at all currently? It's around 3-5C here.

I have dug out some Allen keys and will adjust the mixture tomorrow.

I would have to look up the specs for the thermotime switch, i seem to recall under 10C it operates for up to 8 seconds from first switch on and switches off once the coolant temp is above 10C regardless. Might be wrong on the temperature but fairly sure that's correct.

[Juular]

Right, nothing wrong with the thermotime switch, although I reckon I actually have a coolant temperature sensor rather than a switch. It's a VDO unit that has changing resistance with temperature. Anyway, the readings are plausible and the CSI doesn't appear to be misbehaving so I have ruled that out for now.

A combination of adjusting the idle speed and the CO screw has it idling very smoothly now at around 750rpm. Less rich smelling too. Excellent!

However.. I seem to have a vacuum issue, in that there appears to be very little. When I hit the brake pedal the idle drops to around 500rpm and almost stalls.

The booster itself seems alright - as does the one way valve. I can't see or hear any actual vacuum leaks. When I pull the valve out of the booster after stopping the engine there is a healthy whoosh as there should be.

Pulling a vac hose off the manifold, you'd expect to hear a change in RPM but there's no change. In fact putting my finger to the port I can't feel any vacuum. Is that normal? On my C70 a vac line will cling to your hand.

Are there any sneaky vac lines prone to leak that I should check?

[Laird Scooby]

Originally Posted by Juular

Right, nothing wrong with the thermotime switch, although I reckon I actually have a coolant temperature sensor rather than a switch. It's a VDO unit that has changing resistance with temperature. Anyway, the readings are plausible and the CSI doesn't appear to be misbehaving so I have ruled that out for now.

A combination of adjusting the idle speed and the CO screw has it idling very smoothly now at around 750rpm. Less rich smelling too. Excellent!

However.. I seem to have a vacuum issue, in that there appears to be very little. When I hit the brake pedal the idle drops to around 500rpm and almost stalls.

The booster itself seems alright - as does the one way valve. I can't see or hear any actual vacuum leaks. When I pull the valve out of the booster after stopping the engine there is a healthy whoosh as there should be.

Pulling a vac hose off the manifold, you'd expect to hear a change in RPM but there's no change. In fact putting my finger to the port I can't feel any vacuum. Is that normal? On my C70 a vac line will cling to your hand.

Are there any sneaky vac lines prone to leak that I should check?

If you have a coolant sensor in place of the thermotime switch, it won't pass the current needed for the CSI so worth double-checking the wiring to make sure you haven't pulled the temp gauge sensor.

It sounds as if either your servo or the non-return valve is shot from what you say about hitting the brakes. As for that stub that presents no vacuum, clean it internally with some carb & air intake cleaner and a piece of stiff wire or a small drill bit. It should alter the idle when removed and could be that it's not operating something that it should. It will either be going to the PCV system or the vacuum advance on the distributor, both of which will effect the running, especially at idle.

[Juular]

Originally Posted by Laird Scooby

If you have a coolant sensor in place of the thermotime switch, it won't pass the current needed for the CSI so worth double-checking the wiring to make sure you haven't pulled the temp gauge sensor.

It sounds as if either your servo or the non-return valve is shot from what you say about hitting the brakes. As for that stub that presents no vacuum, clean it internally with some carb & air intake cleaner and a piece of stiff wire or a small drill bit. It should alter the idle when removed and could be that it's not operating something that it should. It will either be going to the PCV system or the vacuum advance on the distributor, both of which will effect the running, especially at idle.

I'm fairly certain the non return valve is alright - I took it off and tried blowing through it, it does seem completely airtight one way.

If the booster was gone would I still get the whoosh of air after leaving the engine off for a while? That sounds like it's retaining vacuum acceptably well?

Good idea on cleaning the ports. I've also pulled the throttle body and flame trap and I'm giving them a good clean.

Didn't see a gasket on the throttle body. Normal?

Is the PCV a common source of issues on these?

Didn't realise there were two temperature senors but that makes complete sense.

The car starts and idles without the CSI plugged in so I'm going to leave that out of the equation for the moment.

Thanks for the feedback.

[Laird Scooby]

Originally Posted by Juular

I'm fairly certain the non return valve is alright - I took it off and tried blowing through it, it does seem completely airtight one way.

If the booster was gone would I still get the whoosh of air after leaving the engine off for a while? That sounds like it's retaining vacuum acceptably well?

Good idea on cleaning the ports. I've also pulled the throttle body and flame trap and I'm giving them a good clean.

Didn't see a gasket on the throttle body. Normal?

Is the PCV a common source of issues on these?

Didn't realise there were two temperature senors but that makes complete sense.

The car starts and idles without the CSI plugged in so I'm going to leave that out of the equation for the moment.

Thanks for the feedback.

There's a second valve within the servo that lets air in as you press the brake pedal, if the diaphragm seal in the servo has gone (most common cause of servo failure, when this second valve opens it's like opening the inlet manifold via the brake servo vacuum hose. That means the servo can still hold vacuum until the pedal is pushed then air rushes in via the valve as the pedal is pushed, through the diaphragm and down the brake servo vac line. Had one go that way on my Rover a few years back. Was a bit of a fiddle getting the servo past the master cylinder but i managed to swap it without removing the m/cyl - the Volvo looks easier in this respect.

The flame trap is part of the PCV system as well and the oil separator on the left side of the block. Blockages in it can cause rich and/or lumpy running and a good move cleaning the throttle body too. The PCV system is a common problem on redblock engines, always has been, even on the OHV version but on the OHC, even moreso as it is more enclosed and more critical to correct running.

Usually the temp gauge sensor is towards the front of the head, i wonder if the thermotime switch has been replaced at some point with a temp gauge sender? Wouldn't surprise me!

[230ina245]

"Usually the temp gauge sensor is towards the front of the head, i wonder if the thermotime switch has been replaced at some point with a temp gauge sender? Wouldn't surprise me! "
From memory that shouldn't be possible as they are different sized threads.
The temp gauge is a smaller sender with the bigger thread.
Tim

[Laird Scooby]

Originally Posted by 230ina245

"Usually the temp gauge sensor is towards the front of the head, i wonder if the thermotime switch has been replaced at some point with a temp gauge sender? Wouldn't surprise me! "
From memory that shouldn't be possible as they are different sized threads.
The temp gauge is a smaller sender with the bigger thread.
Tim

You may well be right, memory can play tricks on all of us and it's a long time since i was under the bonnet of a 240 with cold start problems!
The 7/9xx models use a different system (except the 740GLE and one or two late model 740s with the B200E) that does it all with an ECU and a CTS so trying to think back further than those is a bit of a challenge sometimes!