406oc.co.uk

I've just started to pull bits off to get to the cambelt on my 406 auto, the belt and water pump were replaced by a local garage about 2 years back but when the car came back it had some belt noise which I thought was just because it was a new belt bedding in.

Thinking about it now due to the water pump bearing now squealing I'm thinking the belt was probably over tensioned, is this a possibility?

Replacing the belt and pump is not beyond my capabilities but my old 18 volt torque gun decided to have a smoke up when trying to undo the crank pulley bolt so I have stalled for now. Thinking I could lock the flywheel with an 8mm bolt to try and have a go at the pulley bolt with a bar and socket I was miffed to find no hole in the engine block to pass the bolt through into the flywheel! There are two m6 threaded holes facing forward on the casing near the starter motor aperture though which I'm guessing is for a toothed locking tool to fix to. Is this the norm on the auto and would anybody know what the locking tool part number is please?

I was hoping to get the job done over the weekend but should have known the crazy Frenchmen would have put something in to trip me up

Cheers,

Paul

Now sorted with a good poke around and found the locking pin hole in the block. It was full of crud and not that easy to see first off.

Over tensioning is a possibility, but a more common error is failing to slacken the bolts locking the camshaft pulley to its hub while adjusting the tension. (This allows the tension to equalise on either side of the camshaft pulley, necessary because the tensioner acts on one of the two runs from crank to cam pulleys only).

I suffered exactly this problem when an 'expert' screwed up changing the belt on my first HDi, always did it myself after this.

I always undid the crank pulley bolt with a breaker bar, (occasionally needing an extension tube) and two long extensions allowing you to work outside of the wheelarch. Engine locked by top gear and assistant pressing the brake pedal. Realise yours is an auto so that won't work.

The locking pin holes in the crankcase/flyweel are I believe only intended to prevent the engine turning during timing belt replacement etc. I don't think they're meant to resist the break-out torque of the crank pulley bolt, (which coukld well be 2.5 times the tightening torque).

Bigger/better impact wrench is your best bet, an impact driver isn't going to win.

Doggy wrote: ↑Sat Oct 01, 2022 6:22 pm Over tensioning is a possibility, but a more common error is failing to slacken the bolts locking the camshaft pulley to its hub while adjusting the tension. (This allows the tension to equalise on either side of the camshaft pulley, necessary because the tensioner acts on one of the two runs from crank to cam pulleys only).

I suffered exactly this problem when an 'expert' screwed up changing the belt on my first HDi, always did it myself after this.

You weren't afraid of changing the timing, by doing this?

No. The camshaft is still locked so maintains its position relative to the crankshaft, all your are doing is allowing the camshaft pulley to rotate fractionally with respect to the camshaft in order to allow the belt to be tensioned equally throughout its length. If you dont do it this way the tensioner will tighten the belt between cam pulley/tensioner/crank pulley while leaving the rest of it looser. The camshaft pulley mounting screws have elongated holes for this reason.

https://www.406oc.co.uk/viewtopic.php?f=10&t=17085

Applies equally to 2.0 HDi's.

Surprisingly it's also covered in the Haynes book.

Thanks, good tip and good explanation. Next belt job I will do this. I replaced two belts without doing this, after the last one (on my wife's Citroen) the engine made a grinding sound until I loosened the tensioner roller enough. Although I was not really comfortable with the low tension, at least the grinding sound was gone, so I left it that way. I think now that the initial (correct) tension setting was indeed not balanced on the other side of the belt.

Ignore my last sentences, it seems that Citroen does not have an adjustable camshaft gear. Anyway, thanks for the tip!

Thanks Doggy, I managed to borrow a healthy torque gun and the job is now done. Like Frogs mine did not have the adjustable cam pulley either and a few rotations of the engine showed belt tension was the same between pulley's, idler and tensioner etc, I actually used a phone app (CarlTune) to finally check the tension of the belt as in this video https://www.youtube.com/watch?v=iha-6Sf ... l=FilmesJP

The water pump that had been fitted a couple of years back was very notchy when turned by hand and felt overly tight for a two year old pump, the fact that the guy told me he'd used a Gates Powergrip kit and changed everything didn't ring true to me. The idler pulley and tensioner I removed were not Gates whilst the pump and belt were plus there was no Gates "Cambelt change interval" sticker used in the engine bay which always come with the kits and generally get used by the mechanic doing the job.

Anyway my woes are not over as the car has also been over fuelling and smokes a bit on idle which I think could be a leak on the turbo to intercooler hose, usually I am not able to squeeze the hose flat when the engine is revved but now can do this and hear air pressure escaping somewhere. There is also a whirring noise which seems to be coming from the high pressure pump area.

Thursday looks dry and bright so will get the old girl on the ramps to check for turbo wear or a split hose, the intercooler looks ok fingers crossed!

Thanks again for the advice as it's always good to get another take on problems.

Regards, Paul

okehdokeh wrote: ↑Mon Oct 03, 2022 6:35 pmAnyway my woes are not over as the car has also been over fuelling and smokes a bit on idle which I think could be a leak on the turbo to intercooler hose, usually I am not able to squeeze the hose flat when the engine is revved but now can do this and hear air pressure escaping somewhere. There is also a whirring noise which seems to be coming from the high pressure pump area.

A few years I had a similar issue: no turbo pressure and a hissing sound. Turned out this small rubber sleeve had burst open:

Thanks Frog, I'll check there first The car has recently been de-catted and was told that the lack of back pressure could cause some oil to seep past the turbo seals into the exhaust causing the smoke at idle, to be honest it smells more like diesel smoke due to the the low boost, I'm guessing somewhat though.

okehdokeh wrote: ↑Tue Oct 04, 2022 9:24 pm Thanks Frog, I'll check there first The car has recently been de-catted and was told that the lack of back pressure could cause some oil to seep past the turbo seals into the exhaust causing the smoke at idle, to be honest it smells more like diesel smoke due to the the low boost, I'm guessing somewhat though.

Yes, if the intake air is lost, the engine will overfuel a bit, but I doubt if you would see that at idle, when no boost is being applied.

There wil probably be one or more diagnostic fault code to be read in PP2000. Here are the fault codes on my vehicle at that time:


I think the second one ("Open circuit...") was the result of my experiment to unplug the air flow sensor (MAF), which causes the injection ECU to fall back to running on the boost pressure sensor. I did that in an attempt to reduce of the smoking.

frog wrote: ↑Wed Oct 05, 2022 8:45 am

okehdokeh wrote: ↑Tue Oct 04, 2022 9:24 pm Thanks Frog, I'll check there first The car has recently been de-catted and was told that the lack of back pressure could cause some oil to seep past the turbo seals into the exhaust causing the smoke at idle, to be honest it smells more like diesel smoke due to the the low boost, I'm guessing somewhat though.

Yes, if the intake air is lost, the engine will overfuel a bit, but I doubt if you would see that at idle, when no boost is being applied.

There wil probably be one or more diagnostic fault code to be read in PP2000. Here are the fault codes on my vehicle at that time:

DTC codes boost loss.png


I think the second one ("Open circuit...") was the result of my experiment to unplug the air flow sensor (MAF), which causes the injection ECU to fall back to running on the boost pressure sensor. I did that in an attempt to reduce of the smoking.

Thanks Frog, I have some time today so gonna go through as much as I can, will try unplugging the MAF too and see if that makes a difference. I know in the past I had that fault show on my icarsoft code reader after unplugging it with IGN on, that problem turned out to be the regulator in the high pressure pump in the end.

I thought I'd got this sussed out but there is more to it than I first thought, on the way into town to drop the missus off the turbo started whining and a altogether separate whirring noise from the engine started. The smoking got a little worse especially if you sat at idle for a while and then pulled off.

I managed to get a recon turbo at a good price so thought I'd have a go myself at swapping it out myself, what a b**tard job that was especially working out on the road and dodging the rain showers. I was amazed to find there were no gaskets on the turbo to manifold joint or on the waste gate side but did fit them when the new turbo went on.

Looking down into the oil feed and drain passageway on the old turbo I could see the bronze shaft bearing was loose and had spun round masking the hole and starving the turbo of oil, tbh other than that the rest of the old turbo looked ok. The oil feed banjo bolt filter was clean with no signs of debris so cannot blame that!

I guess what I need to know is what damage could have been caused elsewhere on the engine as I'm already in for a recon turbo, cambelt kit, oil, gaskets and filters plus the blood, sweat and tears I've already shed getting this far.

The car still pulls really well but sounds terrible after it has warmed up and the smoking especially with city driving is not going to be tolerated by the old bill if they pull me over Any opinions and guidance gratefully received chaps

Searching around on the web and there are some suggestions pointing to the head gasket being blown, there is no coolant in the oil or vice versa though. I recently used a diesel fuel system cleaner (Wynn's) and wonder if this could have moved some crud that was sitting in the split gasket and keeping it sealed. I have a compression tester coming so will go over each cylinder when that arrives but wondered are there any oil galley ways near the bores that could bleeding into a cylinder? Crankcase pressure isn't super high but there seems to be more than usual!

Have you checked your injectors? Bad spray pattern/leaky etc will definitely cause smokiness among other things. Injector seals are another thing that go wrong. Do a leak down test as a start. Also check running correction values and injector coding with PP2000.