Peugeot valve clearances?

[Agile]

It has been suggested that my Peugeot diesel starting problems are due to a lack of compresssion. Nothing else that I have not been able to check.

In the olden days tappet clearances became smaller when the engine was hot and the noisy valves gear became quiet after 10 min.

On my 106 the compression seems OK as I have roughly tested it whilst hot! Thats putting on a gentle hill in gear 4 and seeing how fast it moves downhill. That was about 4-5 seconds per cylinder when hot and pretty even.

My starting problem is only since the weather has become colder and its about 7 C in the mornings. Once started it starts up fine all day long. I never had any problem when it was 10-12 C in the mornings.

Now what happens to the valve clearances on modern OHC engines with alloy heads when they warm up?

Tony

 

[Mursal]

Hydraulic tappets allow the clearance to self adjust. You will need a compression test kit to give compression figures when cold.

But as I have said in the past, always do the easy stuff first, even redo it before moving on to a more expensive causes. I have found in the past its the easiest thing in the world to overlook a simple issue especially while working on the vehicle alone.

For example, did you disconnect each heater and test individually? All you need is one dud heater plug, Did you open an injector pipe first thing in the morning to see if you have diesel?

But if you can do a compression test on a hill, I am wasting my time

 

[Burnerman]

Just for interest, the valve clearances for these are (cold):
Inlet 0.15mm Exhaust 0.30mm
I'm pretty sure these are shim and bucket types, and they really aren't a service item anymore......the clearances are only set after cylinder head work.
The compression ratio should be 23:1 and can only be checked with a gauge with all the glowplugs removed. Granted, diesel compression testers are expensive but diesel specialists have them. (For my sins I have a Silverline set )
John

 

[Mursal]

(For my sins I have a Silverline set )
John

Well impressed .......

 

[Agile]

I am totally happy that all the plugs are fine! I have replaced two with new and tested all including the new ones individually. I have also directly powered them for minutes when trying to start the engine.

My starting problem is only since the weather has become colder and its about 7 C in the mornings. Once started it starts up fine all day long. I never had any problem when it was 10-12 C in the mornings.

I am trying to find a cause which is highly temperature dependent.

Now what happens to the valve clearances on modern OHC engines with alloy heads when they warm up?

I appreciate that testing the compression on a hill may not be very techinical but it what is available to me and actually pretty comparable when I have a perfect car to compare with the problem one! Next I have to compare the problem when its cold. That means parking it overnight on my chosen test hill!

Tony

 

[Burnerman]

The valve clearances will reduce a tiny amount when the engine is hot, and this is built into the clearances recommended.
If the engine starting issue is totally heat dependant, then its due to faulty plugs, cranking speed or poor cylinder compressions (yours will need to be between 25 and 30 bar).
Testing compressions your way is like carrying out a flue gas analysis with your nose, if you get my drift!!
John

 

[ahmotorsport]

How many miles has the car done?

If it was poor compression, it wouldn't start at all and if it did, it would sound like a bag of nails.

If you've replaced two heater plugs, why not just buy a set and be done with it?

You can always bench test your heater plugs (power them up for a few seconds, see how hot they get)....For the record, they should be absolutely baking.

Is yours a manual choke or ECU controlled?

 

[Agile]

The valve clearances will reduce a tiny amount when the engine is hot, and this is built into the clearances recommended.

If the engine starting issue is totally heat dependant, then its due to faulty plugs, cranking speed or poor cylinder compressions (yours will need to be between 25 and 30 bar).

John

I was wondering if the valve clearances reduced when cold causing a lack of compression when cold. But that does not now seem to be the cause.

My compression testing, simple as it may be, has enabled me to confirm the compression is fairly balanced between cylinders. It has also confirmed its similar between the good and the bad car!

I keep on telling you that all that the plugs are fine. At least I can test everything about them!

Cranking speed sounds good and perhaps better than the good car.

That leaves the injectors! I know little about those! Could they ever cause poor starting? And only when particularly cold?

Then the fuel input! I hand pump the inlet every time. Is there any pump type fault that could starve the engine when starting cold?

And lastly, any of the last two which, once the engine starts, can enable it to drive OK at motorway speeds?

 

[Agile]

How many miles has the car done?

Is yours a manual choke or ECU controlled?

102 k miles!

A diesel has no choke but the waxstat advances the ignition on cold starts.

I did suspect that early on as it was the only thing that was different when starting cold from the rest of the day when it starts fine.

But I disabled it and it did not solve the problem. There is however considerable adjustment available on the lever and I would like to try adjusting that a little more but dont think its the main cause of the problem. But put off for the moment as I dont have instructions for setting it.

 

[Burnerman]

Injectors with a faulty spray pattern would undoubtably cause poor starting, but it would be accompanied with lots of smoke (non atomised fuel) and this would continue when the engine was running - even when it warmed up.
The injectors on your engine are about as basic as it gets and although a clean up could be useful I don't think there is any problem here.
The fuel priming bulb has a non return valve in it, which prevents fuel returning to the tank. In a morning, one or two hand pumps should bring the system up to pressure.
John

 

[Agile]

Both the good and the bad car engines run well and dont produce any visible smoke from the exhaust.

The bad one obviously does give white smoke for a couple of seconds when it eventually starts caused by the unburnt fuel in the cylinders. But that just indicates to me that fuel is getting injected.

This problem is unusual because there does not seem to be any obvious cause!

A possible clue is that it can fire for a second or two and then dies as if caused by lack of fuel. Any suggestions based on that ?

When it does eventually manage to keep going its obviously not initially firing on all cylinders for a few seconds, in fact exactly as if it had failed plugs!

 

[Mursal]

As a matter of interest, do you have much pressure in the sump when hot and you take the oil filler cap off?

 

[Burnerman]

Both the good and the bad car engines run well and dont produce any visible smoke from the exhaust.

The bad one obviously does give white smoke for a couple of seconds when it eventually starts caused by the unburnt fuel in the cylinders. But that just indicates to me that fuel is getting injected.

This problem is unusual because there does not seem to be any obvious cause!

A possible clue is that it can fire for a second or two and then dies as if caused by lack of fuel. Any suggestions based on that ?

When it does eventually manage to keep going its obviously not initially firing on all cylinders for a few seconds, in fact exactly as if it had failed plugs!

Classic fuel starvation symptoms, that......starting then cutting out.
Have you noticed a bleed nipple on the injector pump fuel supply?
John

 

[Agile]

No noticeable blow back when accellerated with oil cap off.

John, you asked about an air nipple on the fuel supply before but there does not seem to be one where the fuel pipe goes into the pump.

But if it was just air in the fuel would that carry on for weeks ?

Would it not clear on its own on long runs?

How could it only affect starting when the weather cooled overnight to below about 12 C ?

 

[Mursal]

Might be taking in air overnight, if you loosen the injector pipes and bleed (crank over to you see diesel) then go for a start, This is after ensuring all air has been purged out of the injector pump supply (this is usually shown by a hard hand primer).

Cold weather, even the best diesel will be more sensitive to starting issues as the temperature falls.