diesel help

[harryb94]

Black smoke is indeed excess fuel, white smoke is incomplete combustion.

Ahh I see!

 

[rich the mechanic]

Ok shims definitely the correct order I was very careful with that.

Head was skimmed 19thou and I suspected it had been done before and the engineering firm independently said the same the saver shim is 20thou and is like a decomp plate it sits under the head gasket on top of the block.

After a run to work and back the smoke has reduced but still have a rough idle and white tinged with blue at the same time, i did scrape out the EGR valve to shift off an amount of carbon build up.

I was under the understanding that the pump timing was fixed it's fitted with the Lucas/cav pump and injectors but the pump has a tag on it that looks like it says Delphi.

 

[rich the mechanic]

It does need a full service but as I was short on time that had to wait I didn't measure the clearance on the valves.

 

[dannyp]

whilt smoke is defanty unburnt fuel my truck used to be good at white smoke, used to sit there chuging on 1and an bit cylinders in the morning wiht the hand throttel locked out half way. pumping out white smoke that got greyer and greyer until eventuly it's finaly guff out a load of black and rev up.

 

[normspanners]

Going back to your first post you stated that a saver shim was fitted, surely that would mean that all the valve clearances would have to checked and reshimed if needed ?

Why?

as I was short on time that had to wait I didn't measure the clearance on the valves.

And why did n't you check them?, as you are a mechanic, it takes 1 minute, tops, to check, as the cam is fitted and 5mins if you have to wiz the cam cover off. I have marked up buckets and shims in the past and a couple times when mithered by phone calls or people asking just have a look at this. have got confused when dealing with stupid french cars numbered, number 4 at the front of the engine where the real number 1 lives. Why can't they be normal? stupid idea's
check the clearance first, then we can discuss further when we know.

Not sure if the ECU adapts on them, but mine, if you change the exhaust etc, it takes up to 30 minutes of continous cruising to recalibrate itself...

not on one of those they don't as basic as it goes.

Ahh I see!

If you can't see, it probably is the smoke in your eyes, that white stuff stinnnngs like crazy.

 

[colnerov]

I was under the understanding that the pump timing was fixed it's fitted with the Lucas/cav pump and injectors but the pump has a tag on it that looks like it says Delphi.

Hi, there's fine adjustment between the sprocket and the pump shaft. It's either a vernier type adjustment within the sprocket or you loosen the fixings on the injector pump flange and turn the pump body itself. different manufacturers do it different ways.

Colin

 

[normspanners]

Hi, there's fine adjustment between the sprocket and the pump shaft. It's either a vernier type adjustment within the sprocket or you loosen the fixings on the injector pump flange and turn the pump body itself. different manufacturers do it different ways.

Vernier on them. But if pinned shouldn't need to adjust vernier, also rough idle sounds like low compression to me.

 

[rich the mechanic]

And why did n't you check them?, as you are a mechanic, it takes 1 minute, tops, to check, as the cam is fitted and 5mins if you have to wiz the cam cover off. I have marked up buckets and shims in the past and a couple times when mithered by phone calls or people asking just have a look at this. have got confused when dealing with stupid french cars numbered, number 4 at the front of the engine where the real number 1 lives. Why can't they be normal? stupid idea's
check the clearance first, then we can discuss further when we know.

1 is rear but I marked first one out as CBE cam belt end then in order and didn't check clearence as had no option to change at home on a sunday afternoon and valves never left the head as i couldn't find my valve compressor. This is the first diesel I've done anything on the engine to and while a service is needed couldn't see why the clearence would change.

 

[normspanners]

Did you see them do the surfacing ? because some times the valves have to come out THEY may have got order wrong
The other thing is ally swarf in the valve seats from the surfacing, if not cleaned out properly, it can stick on the first crank of the engine, had that on a golf somebody had built was white smoking unbelievably and would not start it was swarf on one of the injector sealing washer.
Some modern diesels the injector washer have to be matched exactly and are measured in thou's if not the same they dont run correctly. ( not yours though)
You should always check valve clearance as you rebuild, because you dont know how much valve recession has occurred, it may have been border line before stripping, also for another thing after a skim, the cam is not actually running true in the head, because the head is not true and straight anymore.

 

[AndyStobbs]

I think the cam can be ruled out. Given the head upper face is used as the datum face for setting the job up, I can't see the camshaft being 'sloped' when its all re-installed.

Bottom line here is you've done a rush job and now you're going to have to take it off again or it'll nag the hell out of you - even if you can live with the issues.

After you re-fitted it all, and rotated the engine however many turns to bring the timing marks back around, did the pins slip in?

 

[normspanners]

Given the head upper face is used as the datum face for setting the job up, I can't see the camshaft being 'sloped' when its all re-installed.

Sorry Andy But--

As the op had to use a shim because so much was removed, you cannot assume the cam will be running the same, speak with Eric I have discussed this at length with him.

Not Checking Flatness

Never assume a head is flat. You can’t tell if a head or block is flat or not unless you measure it with a straight edge and feeler gauge. You should always check for flatness, especially in critical areas like those between the cylinders.

Flatness specifications vary depending on the application, but on most pushrod engines with cast iron heads, up to .003″ (0.076 mm) out-of-flat lengthwise in V6 heads, .004″ (0.102 mm) in four cylinder or V8 heads, and .006″ (0.152 mm) in straight six cylinder heads is considered acceptable. Aluminum heads, on the other hand, should have no more than .002″ (.05 mm) out-of-flat in any direction. On a performance engine, the flatter the better.

If the face of an aluminum head is warped, don’t assume the only way to straighten it is to grind metal off the face until it is flat again. The whole head is warped. If the head has one or two overhead camshafts, the cam bores will also be misaligned in most cases. The best fix here is to straighten the head BEFORE it is resurfaced. This can greatly reduce or possibly even eliminate the need to remove more than a couple thousandths of metal.

Aluminum heads can be straightened by countershimming the head on a heavy steel plate (place shims under either end of the head to offset the amount of distortion), clamping it down, then heating it in an oven to about 425° F for several hours, then letting it slow cool. The goal is to get the cam bores straight. Once they are in alignment, chances are the face of the head will be reasonably flat, too, and require minimal machining to refinish the surface.

Another method for straightening aluminum heads is to use a torch to head the top of the head, starting in the center and working towards the ends. The trick here is to keep the head temperature under 500° F to prevent softening the head too much.

Quote from :-

http://www.enginebuildermag.com/200...avoid-when-resurfacing-cylinder-heads-blocks/

As per above if a well warped over head cam head is straightened by skimming, the head is still warped, the face now isnt but the head therefore the cam bores still are.


As this engine is now also rattly the shimming NEEDS CHECKING FIRST. because the valves could be clipping pistons

 

[normspanners]

If the head needed say 10 thou off it originally because it was warped that much, the head is now ten thou out of shape the face is straight though, this can because of the centre cam bearing wear,may now tighten the centre valves clearance, if marginal before, they will be tighter now, and possibly hold valve off the seats which will get worse as it warms up.
But if the head had 19thou this time or even more off to need a20thou head shim that would also be using the thickest gasket, I assume, and if the valves also have no clearance 8-10 thou they could now be 20 thou closer to the pistons on full open ie from valve seat.

 

[normspanners]

These engines are well known for valve seat recession

PS A few years ago I bought a 206 for pennies same engine,BTW, the guy had been told by several garages it would not start because the fuel solenoid was faulty, it drove in one night and would not start the next ( wintertime btw) I cut off the armour changed the solenoid, but still would not start, sounded fine cranking, just would not crack up, checked shimming everyone was tight i re shimmed it, and it started ran rough for a while till it cleaned the carbon off the valve seats then ran fine for years

 

[AndyStobbs]

It can only be twist though, around the cam shaft axis. Else the camshaft would be bent once installed and would wear the journals in no time.

 

[normspanners]

It can only be twist though, around the cam shaft axis. Else the camshaft would be bent once installed and would wear the journals in no time.

Why ?
Ally heads bow usually upwards in the middle, and they do bend the cams, I am afraid, if you read the quote above and below it explains it perfectly, on a skimmed well warped head the cam can be a 10- 20 thou out and I have known cams to break due to fatigue after being run in a bent head.

When overhead cam heads get hot, they often swell and bow up in the middle. This may cause the OHC camshaft to seize or break as well as cracks to form in the underside of the head. Pushrod heads are not as thick as OHC heads so are less vulnerable to this kind of stress and warpage. But even pushrod heads have their limit, and when pushed too far will also warp and crack.

quote from http://www.enginebuildermag.com/2012/01/cylinder-head-repair-methods/

 

[normspanners]

Aluminum heads are especially vulnerable to warpage and cracking because aluminum has a much higher coefficient of thermal expansion than cast iron. Consequently, when a bimetal engine with an aluminum head gets too hot, the head tends to swell up in the middle, causing it to warp and blow the head gasket. If the engine has an overhead cam, the resulting misalignment in the cam bores created by the warpage can gall or seize the cam bearings, or even break the cam. Anytime you encounter a warped or cracked aluminum head, or an OHC head with a seized cam, chances are the damage was caused by overheating.

quote from http://www.aa1car.com/library/us697.htm

And by skimming it, the head remains bent, it tightens properly on the block face because that face is now artificially flat, but the head structure is still bent.

 

[AndyStobbs]

I can see what is being said, but can't apply it to a run of the mill situation. If it was causing problems heads wouldn't be getting skimmed at all.

Massive generalisation to say that heads usually bow upwards in the middle. There are other reasons and failure modes for/of having a head skimmed, not always because it has seen serious heat - and warpage.

 

[colnerov]

Hi, the thing is skimming heads is a historical practice from the days of side and overhead valve engines which are more tolerant of this. Just because it's been done in the past does mean it can still be done regardless. OHC engines can and do especially Peugeot for breaking cams and cam caps or carriers.

Colin

 

[normspanners]

Massive generalisation to say that heads usually bow upwards in the middle.

Usually the car overheats and warps the head, the gasket goes either first or last, ie chicken / egg syndrome and the heads warp because of overheating in some fashion.
Call Eric H and ask him, most heads bow up and should not really be skimmed if more than a few thou out, most people/ garages get away with it, because of wear in the engine but on competition high rev'ers there is a very good chance of cam breakage.
It is a very real problem that is why it is mentioned above in the quotes

 

[normspanners]

Also if 20 thou or more (because we dont know if the heads been skimmed before this) has been skimmed off this time, peugeot heads are VERY close to needing the valves taken out of one and four to skim, therefore there is a good chance they could have been mixed up, if the apprentice put them back in, number 1-4 synario again , the same thing as LR discovery heads having masses skimmed off , also on the peugeot's the seats are easily distorted in the head by heat and should be vacci tested before building, this is of course all down to expense and expertise.