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Discussion Starter #1
This is a picture of my valves after brand new replacement and only 600 miles driving. As you can see one inlet port is filthy again whereas the rest are still as new. What gives???? The dirty port is 2nd from left as you look from front of car
 

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Hi Si!
My money would be on combustion products leaking past the valves on that cylinder.

If the valves have just recently been replaced the culprit could be one of two possibilities:
1. Grinding in of the valves not done properly on fitting.
2. Cam follower mechanism not reassembled properly on that cylinder causing the valves not to close fully when they're supposed to.

I might ask the question of why you had the valves replaced. Was it because of blow-by on one of the cylinders? And if so, was it on that cylinder?
 

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Discussion Starter #3
Thanks for the reply! Great advice I can look into those. What happened was the garage did the timing chain incorrectly and it slipped on the motorway and completely smashed every single valve. So..... they had to rebuild it. But they reused the followers so could those followers maybe be slightly damaged?? It's funny though how it's both valves on that one inlet. If if was only one of them I'd say yeah it wasn't lapped in or maybe a crappy valve spring or something but as it's both it seems like this would be too big a coincidence??? Really scratching my head tbh lol.
 

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Hi Si,

You read my mind exactly. If a valve had been poorly lapped it might be just one of the two that would be tarnished. But here we see both.

With a bent part in the cam follower mechanism it would affect the pair. And let's face it, these engines have a complicated mechanism with some fine tolerances going on.

Having heard your reasons for having the work done (ouch!) I think we know the prime suspect. Now, time to get it fixed...
 

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So if I was Si, my first plan would be Will's idea of a compression test to check the poorly lapped valves theory. Certainly the easiest thing to do.

I'm disturbed by the thought of a lobe turning on the shaft. I suppose you could compare the degrees BTDC that the inlets start opening on the good cylinders compared to that of the bad cylinder. I might use the following method:

I would insert a rod into a sparkplug hole until it touches the top of the piston. Turn the engine by hand until the inlet valves on the cylinder start to open and measure the length of the rod. The length should be the same on all four cylinders at the point when the inlet valves start to open. If the length is different on the bad cylinder then I would say the lobe had turned :D
 

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So if I was Si, my first plan would be Will's idea of a compression test to check the poorly lapped valves theory. Certainly the easiest thing to do.
Not a compression test.. a leak-down test. Very different tests.

Compression test is not going to properly display leakage past valves, it is more of a broad brush type test to find more major compression problems. A leakage test will, as you are able to measure how much leakage each cylinder has and hear where leakage is coming from, by probing the various points on the engine.
 

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Discussion Starter #11
Ok so once I put it all back together I assume the garage can test for leak? If it is the cam then I guess it's going to be new cam... ??? This is all beyond my level of knowledge ???
 

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How does the vehicle run ? Is it smooth ? Any codes for identified cylinder misfires
Do these run mass air flow or map sensor ?

Do these run egr ? Where does the egr port feed into the inlet manifold , where does the crankcase ventilation pipe feed into the inlet manifold ?
 

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Discussion Starter #15
I've had the turbo reconditioned as the boost was all over and I've ordered new boost control solenoid to see if that fixes all that. But it never seemed to cough while it was running or bog down. The pcv feeds In on the side of the manifold opposite side to the dirty inlet port
 

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Is the one way check valve operating ok on the pcv or inlet manifold , what can happen is that when the manifold goes under positive boost the check valves leak so the block can become pressurised with boost , this then can blow excessive oil mist up into the inlet tract and the valves which are closest to the pcv pipe gets most of the oil mist . Does it smoke at all at idle or under boost ?

I’ve seen the cam lobes getting knocked round on the cams but generally the engine will run very rough and the cylinder misfire counter will pick it up the the cylinder contribution is off .

The valve seats could be leaking but again I would of thought if that they are leaking bad enough for blow by it would be running rough and again the missfire counter would pick it up .

When it’s idling if you take the oil filler cap off how heavy is the engine breathing, I have seen pinched rings or distorted piston skirts after piston to valve contact ,, generally the engine uses oil but doesn’t really show in individual ports like you have .

Like already said It’s worth doing a compression test and a cylinder leak down test to get a view of how good the cylinders are sealing .
 

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Discussion Starter #17
I've removed the pcv on mine but it's just a pipe on mine no valves that I can see but I'll look again. I've cleaned the dirty port today with brake cleaner and all that is left is burnt on carbon on the back of the valve faces. No smoke at idle and a tiny bit before when revved but the turbo was leaking slightly when I took it for refurb. I've ordered a leak down tester now on eBay. It'll be here by next week latest. Thank you for all this insight guys I really really appreciate it. Also with the camshaft. Isn't there one lobe for each valve?? So like with the not being lapped in theory isn't it unlikely only those two lobes on the two valves of the same port got pushed round but none of the others?? But I'll deffo get this leak tester and look into it. This is beginning to make for some good education for me and although it's a pain im enjoying what I'm learning!!!
 

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very common issue a garage messing up the timing on these cars! if at all possible I wouldn't go anywhere near them for a rebuild unless they are paying for it and even then I would want it checked by someone who knows what they were doing!

re the inlet valves, when we walnut blast them its always cylinders 4 or 3 that seem to have the worst of the build up, from the pics yes there is a difference but its not going to have any noticeable difference in performance you will see on the road or even if car was put on a dyno.
 

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Discussion Starter #20
So you think it could just be the oil burning to the back of the valve?? I've bought the pcv blocking caps from Peugeot so I'll see if it still happens once I've stopped that. Going to be a lot of trial and error. But good info to know for future!
 
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