Bringing a 740 back to life

[Laird Scooby]

Originally Posted by TonyS9

On the 940 if you have no speed signal getting to the fuel ECU it will raise the idle rpm to over 1500 after you use full power. I have no idea if this applies to your car, but I'd definately look at the pickup wiring going into the rear axle to start with.

It's a 1990 740 n/asp with the B230F Tony.

[Challo]

Originally Posted by Laird Scooby

Fixed the rotation for you Chris.

What were the emissions? Being a 1990 car it can go up to 3.5%CO and 1200ppm HC so anything below that should have passed.

On the air filter, there's likely a convoluted aluminium hose running all the way to the exhaust manifold, if it's still there and intact, disconnect it from the air filter. THere's meant to be a thermostatic flap valve inside the air filter intake but the 'stat fails so it pulls hot air from the exhaust enriching the mixture as a result. Also get the engine idling, remove the vacuum hose from the FPR (Fuel Pressure Regulator) and put your thumb over the open hose. Observe the stub on the FPR to see if any fuel comes out, if it does you need a new FPR and that's the most likely cause of rich running, if it is indeed running rich - many of the 90-92 740s have emissions exemptions, worth asking the tester to check as it's more common than you might think!

It appears the 1992 740 with the B230F had higher limits than the usual for that year, nothing before that though so safe to assume that even with the cat on yours, it should be 3.5%CO and 1200ppm HC :



https://assets.publishing.service.go.../section-1.pdf

Link to the origin .gov document, you want Pg162 for yours.

Bulbs - remove then and check to make sure the filament is ok, if so rub the end contacts on your jeans to clean the, the side of the bulbs the same, clean the bulbholders and refit (note the staggered pins on the stop/tail bulbs, make sure you get it in the right way which should be easy, very hard if the wrong way!).

A small amount of welding and have a word with Luke aka 360beast about a battery clamp and bolt.

Front brakes, undo the bolts on the guide pins assuming you have the single piston sliding caliper and remove the guide pins, clean them with a wire brush and use silicone or copper grase to lube them. While they're out, remove each pad one at a time, clean the edges of the pads and where they sit in the caliper, again some copper grease on the edges where they contact the calipers (don't get any on the friction material! ) and that will probably fix them.

Clean the throttle body, AICV and PCV system again, make sure there are no air leaks into the inlet, a silly question, you haven't touched the hard to reach throttle stop screw have you?

Rack gaiter, good call, fit a new one and have done for now. Meanwhile investigate what other problems are present on the rack and maybe consider a reconditioned rack, probably cheaper and easier in the long run that faffing about renewing parts that might be redundant if the rest of the rack is unseviceable.

Thanks I will make a start on the list.

On the idle I haven’t touched the throttle screw at all, just been refreshing the hoses, and giving everything a clean.

I do remember the tester mentioning that when he went to do the emissions the machine told he him not to use the probe in the exhaust, so perhaps my car is exempt?

[Laird Scooby]

It still needs a test Chris even if it has the exception to the emissions. It still needs to be under the limits i listed above but it's common for the emissions analyser to go into a self-calibration mode during the test and to tell the tester not to insert the probe, especially during a BET test. I think it does it on the cat test too but it's a few years since i had a car with a cat test although my Rover has one it qualifies for the exemption/exception so i've never taken much notice of the cat procedure.

[Challo]

Volvo has gone to the mechanic's this morning to get the rust repaired, and for him to check over the callipers. I know the brakes are a relative easy check, but I just ran out of time due to work and family.

I checked the FPR and this seems to be ok, no fuel could be seen when i placed my finger over the hose. Its defiantly still running rich though, and after a drive the idle sticks about about 1200-1500k rpm. My mechanic is going to check this and see if he can notice anything, same with the leak potentially coming from the steering rack.

He did suggest it might just need a good blast on the motorway to get everything up to temp for a prolonged period of time.

Will find out later when he reports back.

[Laird Scooby]

Originally Posted by Challo

Volvo has gone to the mechanic's this morning to get the rust repaired, and for him to check over the callipers. I know the brakes are a relative easy check, but I just ran out of time due to work and family.

I checked the FPR and this seems to be ok, no fuel could be seen when i placed my finger over the hose. Its defiantly still running rich though, and after a drive the idle sticks about about 1200-1500k rpm. My mechanic is going to check this and see if he can notice anything, same with the leak potentially coming from the steering rack.

He did suggest it might just need a good blast on the motorway to get everything up to temp for a prolonged period of time.

Will find out later when he reports back.

Makes me wonder about the CTS but as the car has disappeared out of your possession temporarily, you can't check that.

An Italian decoke may well help too, maybe if your mechanic has trade plates he could try that for you.

[Challo]

Originally Posted by Laird Scooby

Makes me wonder about the CTS but as the car has disappeared out of your possession temporarily, you can't check that.

An Italian decoke may well help too, maybe if your mechanic has trade plates he could try that for you.

Can you advise what the CTS means?

I'll see what he comes back with later today and any advice he gives.

[Laird Scooby]

Originally Posted by Challo

Can you advise what the CTS means?

I'll see what he comes back with later today and any advice he gives.

Coolant Temperature Sensor Chris, it's about halfway along the head under the inlet manifold between #2 and #3 inlet tract. It tells the ECU what temperature the engine is so the ECU can adjust the mixture accordingly.

See what he comes up with later...........

[Challo]

Originally Posted by Laird Scooby

Coolant Temperature Sensor Chris, it's about halfway along the head under the inlet manifold between #2 and #3 inlet tract. It tells the ECU what temperature the engine is so the ECU can adjust the mixture accordingly.

See what he comes up with later...........

Mechanic phoned with his update.

Rust - All sorted. It had been patched before, but looked a pretty shody job. All cut out and new plate welded in.

Running Issues - Looked the car over and didn't think it was running rich. Advised the exhaust is a little sooty, but that could be a build up for the issues before. He advised the high idle potentially was a sticking throttle cable. It was sticking open slightly, so he removed it and cleaned it all up and seems to be running well now. He did suggest a good run would certainly help clear out any rubbish.

Brake Callipers - The car has duel pistons, and on each side one of the pistons is seized. He said some of the gaskets have spilt and need replacing. I'll grab a refurb kit from PFV and get him to strip it down and rebuild for me.

Steering Rack - MOT mentioned play and he said yes there is a little bit of play but nothing to worry about. He did mention that when turn right it did feel like it had a pinch point, but nothing serious.

Engine Leak - There was a slight leak under the engine. I thought it was from the rack, but he said actually its from the engine. Looks to be a small leak from the crack case, and also one from the gearbox bell housing. Again nothing serious, just to keep an eye out it.

Overall seemed happy with the car, just need to get those parts ordered on the rebuild kit.

[tofufi]

Originally Posted by Challo

Steering Rack - MOT mentioned play and he said yes there is a little bit of play but nothing to worry about. He did mention that when turn right it did feel like it had a pinch point, but nothing serious.

Mine has this, just the tiniest amount. I know the UJs on the steering column can seize, so intend to try that as a first course of action.

[Laird Scooby]

Originally Posted by Challo

Mechanic phoned with his update.

Rust - All sorted. It had been patched before, but looked a pretty shody job. All cut out and new plate welded in.

Running Issues - Looked the car over and didn't think it was running rich. Advised the exhaust is a little sooty, but that could be a build up for the issues before. He advised the high idle potentially was a sticking throttle cable. It was sticking open slightly, so he removed it and cleaned it all up and seems to be running well now. He did suggest a good run would certainly help clear out any rubbish.

Brake Callipers - The car has duel pistons, and on each side one of the pistons is seized. He said some of the gaskets have spilt and need replacing. I'll grab a refurb kit from PFV and get him to strip it down and rebuild for me.

Steering Rack - MOT mentioned play and he said yes there is a little bit of play but nothing to worry about. He did mention that when turn right it did feel like it had a pinch point, but nothing serious.

Engine Leak - There was a slight leak under the engine. I thought it was from the rack, but he said actually its from the engine. Looks to be a small leak from the crack case, and also one from the gearbox bell housing. Again nothing serious, just to keep an eye out it.

Overall seemed happy with the car, just need to get those parts ordered on the rebuild kit.

If he's going to be stripping the calipers, get him to order the bits, either from PFV or Bigg Red - there are many different calipers fitted depending on the exact model, year andwhether it ha ABS or not, it would seem yours doesn't have ABS though if it has dual-piston calipers - again a very strange arrangement where the inboard side (i think) of the calipers have dual-pistons, the outboard side has a single piston.
Other calipers can be single piston sliding caliper or twin piston caliper (one in, one outboard) and variations on those themes happen with age, and other factors.

When you get the car back, locate the steering column in the engine bay and towards the bottom you'll find a UJ (universal joint). Spray that with penetrating oil and work the steering from lock to lock several times. Afterwards spray it with a heavier lube, thicker oil or spray grease and work that in my the lock to lock procedure. It could also be a sticky top mount on the suspension struts but that will loosen with use usually.
Sometimes wear in the rack that traditionally causes a sticky point is in fact the UJ in the column and many people have found this.

Engine oil leak - add 0.5L Carlube ATF-U to the engine oil. When you do an oil/filter change, after draining the old oil and fitting the new filter, add 0.5L ATF-U first then top up with your choice of 10W40 semi-synth. This will help condition the old oil seals and revive them, frees sticky valves, piston rings, revives the valve stem seals, cleans the engine gently and generally improves things inside. Until the old dirt in the engine is all gone, the oil/filter changes will show dirty oil but it will get cleaner over the years. Adding 0.5L ATF-U each oil/filter change will keep the seals in good condition and the engine clean.