Re-seating valves - PG engine

[Alex_G60_Fanatic 0]

been watching this -

 

The chap makes it look pretty simple but I was wondering is this something that can be done on a drive way with the engine in-situ?

 

The reason for thinking i could do with this is that I ran some pressure tests on the car a few months back and I was getting about 8-9bar on all cylinders except one where I was getting about 6ish. Was thinking this could be a likely cause and a good place to start as the car has been sat idle for the past 2 years anyway. Not taken a look at the pistons themselves although I do have an endoscope that would fit into the spark plug sockets.

 

Also, if there is anyone in the Dundee/Fife/Perthshire area who knows what they're talking about (as opposed to me bumbling around the engine bay) then I would love a second opinion :smug:

[swiftkid 1]

Alex... you do realise you need to take the head off to get to the valves? the engine doesn't need to be removed completely to get at the valves but the head needs taking completely off and use a special tool to remove valves, don't want to teach you how to suck eggs if you know all this, just making sure. I'd take the head off and take it somewhere warm to do it because you will be there a while lol.

[Alex_G60_Fanatic 0]

ooo no no... I NEED to be told how to suck eggs.... I thought you just needed the cam cover and the cam out, not the entire head! Maybe I'll leave this to a professional! does anyone have any idea the costs involved? I assume if the head comes off then It'll need to be skimmed and new gaskets etc...

 

---------- Post added at 12:44 PM ---------- Previous post was at 12:29 PM ----------

 

I think i'm getting confused between cam seals and valves... Was going to try changing the cam seals! ... I'll get my coat..

[swiftkid 1]

Lol ok alex, well seeing as I have started. The valve heads (the bit that you stick the sucker to) is at the bottom of the head, you need to remove the cam to be able to remove the valves but you need to remove the head to get to the bottom of the valve, otherwise you can't get any grinding paste onto it.

 

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That image pretty much explains it, ideally yes it needs to be skimmed and definitely a new head gasket and head bolts. I think I paid £70 to get my head skimmed at my local engineering place but if your wanting to do it, get a quote first.

 

I think I'm getting confused with what your trying to change!? if its low on compression its either a valve or a piston, dunno what you mean by cam seal, do you mean valve stem oil seal?

Edited August 3, 2011 by swiftkid

[davidwort 0]

Alex, was the compression test done with the engine warm and was a 'wet' test done with a little oil squirted into the cylinders to compare to a dry test, this might help indicate if the problem was piston ring related or valve related on the 'low' cylinder, before you start ripping the head off.

[P3rks 11]

I just had my G60 head pressure tested, skimmed, cleaned and valves lapped/re-seated whatever you want to call it and some new stem seals put in (I supplied the seals) for £100 cash in hand at a local engineering firm.

 

It can be done on your own easily and I've done it before to a few engines.. It's a long, laborious pain in the arse job though.

 

But it does require the head off top be done properly. You'll need a valve spring compressor which effectively holds the valve from the underside (hence head off) and pushes the valve washer (can't remember what you call it) down to reveal x2 colletts which require a magnet to get out. then the valve just drops out. You do this 8 times obviously. It's fiddly and annoying.

 

Then you can re-lap/seat the valves.. So re-insert the valves, place some grinding paste on the valve/seat and then use like a rubber/wood suction tool which sticks to the underside of the valve to grind.. Imagine your trying to start a fire so you twist the wood/rubber suction tool in your hands which twists the valve and uses the grinding paste to re-seat the valve. There are usually two grinding pastes (one coarse one fine).. You need to spend a good 10-20 mins on each valve. So it's a pain in the arse job and expect sore hands unless you masturbate a lot and you have thick skin.

 

All in all, it's worth £50 to pay someone to do it.

Edited August 3, 2011 by P3rks

[davidwort 0]

Just a dry test just now mate, from a warm engine. So you would suggest doing a "wet" test? after doing another "dry" test? Do i just squirt a little engine oil into the spark plug hole?

have a quick google for compression test, plenty of info, it just needs a little drop of oil to help seal the piston rings, if you see a difference from dry and wet on that cylinder then it would point to rings and not valves/seats.

 

this might make valve lapping a bit easier, need a low speed drill though! http://www.amazon.co.uk/gp/product/B0012MCW06/ref=pd_lpo_k2_dp_sr_1?pf_rd_p=103612307&pf_rd_s=lpo-top-stripe&pf_rd_t=201&pf_rd_i=B000UZ02EO&pf_rd_m=A3P5ROKL5A1OLE&pf_rd_r=1GY4M2QA9JQQZMM48CJX

 

apologies for your post delete, not sure what happened there, there was a dupicate post showing and then both went???

Edited August 3, 2011 by davidwort

[Alex_G60_Fanatic 0]

have a quick google for compression test, plenty of info, it just needs a little drop of oil to help seal the piston rings, if you see a difference from dry and wet on that cylinder then it would point to rings and not valves/seats.

 

this might make valve lapping a bit easier, need a low speed drill though! http://www.amazon.co.uk/gp/product/B0012MCW06/ref=pd_lpo_k2_dp_sr_1?pf_rd_p=103612307&pf_rd_s=lpo-top-stripe&pf_rd_t=201&pf_rd_i=B000UZ02EO&pf_rd_m=A3P5ROKL5A1OLE&pf_rd_r=1GY4M2QA9JQQZMM48CJX

 

apologies for your post delete, not sure what happened there, there was a duplicate post showing and then both went???

 

Clever little bit of kit that! I'll re-test the preasures and go from there i think! :)