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Author Topic: Inlet cam swap  (Read 480 times)

Offline g0rdo32

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Inlet cam swap
« on: June 06, 2021, 02:32:05 pm »
I'm in the midst of changing out my inlet cam due to a cam followe failure. Lobe was very worn and hpfp is shot.

Just completed swapping the cam out and got a new chain and adjuster on. As I turned on the engine over by hand it stopped and I was unable to move it further. I'd moved it about 1/3 a turn on the cam from the marks on the chain. Obviously worried something might be out now.

I marked up the old chain and transferred the marks to the new one. Same for the cam teeth. I also used a cam locking tool which I check again before trying to turn over.

Not sure whether to carry on reassembly or stop? Any thoughts?

Offline Pudding

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Re: Inlet cam swap
« Reply #1 on: June 11, 2021, 09:06:51 pm »
I would start from scratch with the timing to out-rule piston to valve contact.  If the engine turns freely in either direction until it hits a hard stop, it does sound like parts colliding.

The chain isn't long enough to bunch up and bind if you turned the engine anti-clockwise, so probably isn't that.


2007 ED30 | Ohlins Coilovers | Revo Map | Plus some other stuff | Is all a GTI needs :-)

Offline g0rdo32

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Re: Inlet cam swap
« Reply #2 on: July 27, 2021, 08:07:16 pm »
Thanks for the advice @Pudding . Managed to get it turning over smoothly by hand after a bit of persuasion.

Got it back together again and started today. Idle was very lumpy and had a tappet sound similar to when the follower had gone. sh*t it off quickly when I heard that. As I said, timing tool was used and confirmed before reassembly.

The thought of another strip down is not very appealing but might be the only option?

Offline g0rdo32

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Re: Inlet cam swap
« Reply #3 on: July 28, 2021, 08:17:29 am »
More investigation last night and I found cracks in the breather pipe to the PCV so got replacements on order. Hope this will sort the idle issue.

Not sure about the tappet noise though?

Offline Octoparrot

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Re: Inlet cam swap
« Reply #4 on: July 28, 2021, 10:09:29 am »
Sorry but I think you've bent a valve.

Offline g0rdo32

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Re: Inlet cam swap
« Reply #5 on: July 28, 2021, 02:28:19 pm »
Hi @Octoparrot all the cylinders were tested before I stripped down and had good test. Might be worth testing again to confirm.

I've not had to apply any excessive force to turn the engine by hand. Was slightly stiff to turn initially but it had sat for a while and a drop of oil in the park plug holes seemed to loosen everything up and turn freely.

Offline Pudding

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Re: Inlet cam swap
« Reply #6 on: July 30, 2021, 06:51:12 pm »
Tested before the strip down but the engine bound up when you turned it after fitting the cam?

It could still be a bent valve(s).  I know it's a complete ball ache, but you could remove the intake manifold and fill each intake port with petrol at TDC, one at a time, and see if it drips through.  I don't know what petrol's evaporation rate is in open air (which could give a false result if it evaporates quickly) but I can't think of another chemical that wouldn't cause damage if it does drip through into the cylinders?  Even the fluid level doesn't change after an hour or so, you can assume the valves are gas tight.

The only other things I can think of for the noises and rough running are still timing that's off, or maybe swarf from the failed cam/follower has clogged up the VVT adjuster or oil ways to the cams.   Do you have VCDS?  You can monitor the VVT's position with the engine running using that, which would outrule that issue.





2007 ED30 | Ohlins Coilovers | Revo Map | Plus some other stuff | Is all a GTI needs :-)

Offline g0rdo32

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Re: Inlet cam swap
« Reply #7 on: August 08, 2021, 01:31:33 pm »
Did a dry compression test and showed 175psi on the first 3 cylinders. Number 4 was 150 psi.

It's not looking good. I'm in two minds whether to investigate further or get rid of it now.

The thought of taking the intake manifold or taking off the head doesn't set world on fire.

Offline Pudding

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Re: Inlet cam swap
« Reply #8 on: August 13, 2021, 08:47:34 pm »
Not too horrendous.  Factory spec is 14 bar, or 203 psi.  No.4 is the problem child though.  A leak down test would determine if the loss of compression is at the top or bottom of the engine.  If the bottom end, yeah, £££s to do properly.

I find several beers and bassy tunes on my noise cancelling headphones helps with the monotony of stripping sh1t down.


2007 ED30 | Ohlins Coilovers | Revo Map | Plus some other stuff | Is all a GTI needs :-)