Engineering company suggestions for hard valves/seats

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desauld
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Engineering company suggestions for hard valves/seats

#1 Post by desauld » Thu Dec 31, 2020 9:16 pm

Hi,

I have a range rover 4.2 supercharged on gas which I suspect may be developing an issue with the valves/seats. I'm working on diagnosing the problem (missfire when cold) but am considering burnt valves and or seats as a definite possibility. The car has a good Lpg setup well able to deliver enough gas and has a valve saver system installed and it's feeding plenty of fluid, at about 1.5ml per l of gas. The engine is tuned with an over driven supercharger and sees hard work being used occasionally as a tow rig, pulling my track car, which it is well able to do at 100 mph while doing 10mpg..

Anyhow, if I need the heads done, I was wondering who you guys would recommend? I would remove them and refit, so it's just the valves and seats I would need to outsource. Obviously I would want better/harder exhaust seats, and perhaps exhaust valves, not stock soft ones. On previous engine builds I have had Victor rinze special Lpg duty sintered seats installed by a guy, but he has retired. That build saw 200 hp per liter, (Audi 5 cylinder turbo boarded and stroked to 2.5l, making 500hp without issue on gas ) so I know my way round a gas engine.

I know if I left the heads to a local shop I would probably just get a stock rebuild, which I don't want. Anyone with any suggestions?. Just upgrade the seats ( what type) and use new stock valves, or upgrade the valves too? I have used supertech and Ferrea valves in the past in engine builds.

Would you shim the exhaust valves slightly looser than stock 0.25mn?

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Re: Engineering company suggestions for hard valves/seats

#2 Post by LPGC » Fri Jan 01, 2021 12:15 am

This has got to be the same vehicle as the one discussed on the Rangerover forum? Would be a coincidence to have 2 very similar issues on the same model vehicle if not ;-)

Can't advise you of an engineering firm that could do the heads and valves but expect plenty could do that?

There are no gravity fed lube systems, only simple vacuum or forced electronic types, various brands/types/methodologies in both cases. The supercharged engine should have a forced electronic type or it may get plenty lube at low loads but the engine can run without any vacuum for long periods during which it wouldn't get any lube with a vacuum type system.

These engines have wide band lambda sensors and run closed loop operation even well into boost conditions - If you don't have an engine warning light on this would suggest the LPG system is in tune and mixture is correct. But the petrol ECU can apparently be chipped/flashed to prevent MIL light illumination if mixture is wrong and around a decade ago some installers who struggled to get results (without MIL light coming on) may have advised/done an ECU flash. Maybe more likely that the ECU has been flashed if the supercharger sprocket has been changed to increase the boost. If this is the case mixture on LPG under load could be anywhere.

Symptoms similar to VSR can occur if LPG calibration is wrong even when running on petrol. A type of electronic/forced lube systems often fitted with BRC installs injects liquid lube fluid into the feed pipe between reducer and injectors, in my experience this usually leads to premature failure of LPG injectors and even before causing injector failure causes some injectors to inject more lube (and less gas) than others... Less gas when flowing lube because injector outlets are narrow diameter and a drop of lube fluid obscuring this outlet restricts gas flowing through the outlet. When there's a set of 4 injectors on a V8 cylinder bank and some injectors flow more gas than others the cylinders get less gas will run lean while the other cylinders will run rich, running lean can cause VSR on effected cylinders.

Have you checked engine compression? VSR can have negative effects without causing lack of compression but lack of compression would have the worst symptoms, first notable on gas. But then again if there's a problem with the LPG system symptoms are also more likely to be first noted running on gas.
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Re: Engineering company suggestions for hard valves/seats

#3 Post by desauld » Fri Jan 01, 2021 12:50 am

Thanks for the response. I am on the ffrr forum, but haven't posted about any issues there yet. I did post some questions here some time ago. https://www.fullfatrr.com/forum/topic34107-30.html

Can you supply a link to the thread in question?

The conversation of my car has been done in my ownership as was the supercharger rebuild with the smaller pully. It's on a stock ECU map, with all safety elements retained. Engine management light is off, at least untill this missfire. Long term trims are within normal levels.

I am running a vacuum style valve saver but with some important modifications. I have a vacuum regulator fitted which controls the level of vacuum the valve saver sees to 0.9 to 0.95 Bara. Or 0.05-0.1 barg vacuum depending on how you like to quote pressure. I have then setup the valve saver to flow the required amount of fluid through this regulator system. Therefore from idle to 0.95 bara, the engine gets the same amount of fluid. You are correct that it won't get any under boost, but, the intake tract Inc the charge coolers are coated in fluid so the high air flows under load will help drag that into the cylinder. Not perfect, but should be much better than most installs using a vacuum system, or pumped systems with "spiders".

Standard vacuum systems obviously supply most fluid at idle and none at full load/wot, which is the reverse of what's required, but they also relay on the intake being coated at part load, and seem to preform, at least to some degree.

The vehicle operates most of its time in the zone of intake pressure where it's getting plenty of fluid, eg less than 0.95 bar a.

It may not be the seats or valves, but I need to do more fault finding and a compression check and valve clearance check is part of that. Just looking for options should I need them.

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Re: Engineering company suggestions for hard valves/seats

#4 Post by Gilbertd » Fri Jan 01, 2021 10:39 am

Not the same one then. A member on rangerovers.pub, a P38 forum, has recently picked up a 4.2SC L322 at a very good price due to a misfire which he suspects is down to VSR. I've had hardened valve seats fitted in the past (on a different engine) by a local engine reconditioners (Lyndale Engines in Peterborough) but in that case they sourced the seats. If you were to source your own preferred ones, I would suspect virtually any engineering company would be able to fit them for you.
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Re: Engineering company suggestions for hard valves/seats

#5 Post by desauld » Fri Jan 01, 2021 4:26 pm

I found this useful website.

https://www.kmotorshop.com/content/detail/en/30

Previously I have used these in my Audi turbo engine. I would use the HT+ version now but it didn't exist previously.

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Re: Engineering company suggestions for hard valves/seats

#6 Post by desauld » Fri Jan 01, 2021 4:30 pm

Screenshot_2021-01-01-16-28-07-566_com.lonelycatgames.Xplore.jpg
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Sorry, attachment didn't upload in the previous message.

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Re: Engineering company suggestions for hard valves/seats

#7 Post by LPGC » Sat Jan 02, 2021 5:44 pm

Hell of a coincidence with it not being the same vehicle/owner!

I replied to a PM the owner sent me on the other forum, I haven't seen a thread on the other forum (unless Gilbert has). I have told the other owner about this thread, so he might join in here.

Same advice to both - make sure the problem is VSR related before going to the bother and expense of removing the heads.
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Re: Engineering company suggestions for hard valves/seats

#8 Post by desauld » Sat Jan 02, 2021 11:00 pm

Thanks guys for the feedback, and definitely if the other guy joins this thread it would be interested to hear if his issue mirrors mine.

For certain I won't be pulling the heads unless I'm sure it's an internal issue. I have the compression tester located and ready for use tomorrow, but I have misplaced my leak down tester, so need to find that. Could be something as simple as oil down the plug hole around a coil pack. I had the check engine light come back on this morning a few minutes after a cold start, which I could feel the car missing slightly on. ECU says missfire on cylinders 2,4,6 and multiple cylinder missfire, and misfire during first 1000 revs. It's all on one bank I think ( passenger side?) So something going on there. Could even be vvt actuator on that head?

I did over 100 miles on it today with the EML light on using Lpg at motorway speeds with no issues, and once warm no missing at all. Interesting issue... Let's see what presents itself tomorrow.

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Re: Engineering company suggestions for hard valves/seats

#9 Post by desauld » Sun Jan 03, 2021 9:08 pm

Right,

I worked on the bus today and have found the issue. So after pulling a few fuses to let me crank her over and not start I immediately heard she is hurt on one cylinder, that rhythmic sound being interrupted by a speed up due to low or no compression. I hadn't noticed before as she starts up quickly. I started on bank 2, passengers side, as that's what the ECU had pointed me to and got the following:

Cylinder 2 4.9 bar
Cylinder 4 8.9 bar
Cylinder 6 8.2 bar
Cylinder 8 9.6 bar

So clearly cylinder 2 ( at least) is a problem. I lifted the cam cover on that head and internally everything is nice and clean which is good. I'm having issues uploading pictures from my phone here, anyhow. I immediately got the feeler gauges out and moved the engine over so the exhaust valves where closed on cylinder 2. I had about perfect clearance at 0.25mm. I moved the engine over and attempted to measure intake clearance. NIL. None. Not a bit.

Well, this is unexpected. I have NEVER considered the possibility of INTAKE valves receding and sticking open. How bazaar! I had to check this a few times, eg physically check where the exhaust was, eg outside of the head, intake in the center of the vee.

I had previously gathered up the proper tools that are ment to allow you to depress the follower bucket by pressing on its rim and then allow you to remove the inner central disk shim to adjust clearance, but I couldn't get the shim out of the bucket due to the stiction of the oil. I tried brake cleaner, a magnet and compressed air, but it wouldn't budge. I then set the thinnest feeler gauge I have on top of the bucket, 0.05 mm and released the tool. I couldn't remove the feeler gauge as it was compressed between the base of the cam and the shim, so literally there is zero valve clearance on the intake.

Has anyone ever had valve issues in intake valves?? The plugs had a rusty/ red/orange tinge to them which I assume is the valve saver fluid. It's not something I'm used to looking at as it the first engine I have run the fluid in. Normal? The plugs went in just before the gas conversion.

I started to loose feeling in my hands as it's very cold today, so just checked the exhaust on cylinder 4, which might need some adjustments as it's closer to 0.2mm and stopped there. I haven't even started looking at bank 1.

So I need to lift the passenger head at the very least. If I want to fix her. Need to have a serious think here. It's a 15 year old range rover, that's in good order but it's now not worth big money. Fixing this properly won't be cheap.. I do enjoy crusing about in her, and God it can tow. My 3 year old loves it too with the TV's etc.

Anyone ever fit hardened intake seats!??

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Re: Engineering company suggestions for hard valves/seats

#10 Post by desauld » Sun Jan 03, 2021 9:49 pm

Ok, found a way to upload pictures, here goes 2 at a time.
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Re: Engineering company suggestions for hard valves/seats

#11 Post by desauld » Sun Jan 03, 2021 9:51 pm

A few more.
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Re: Engineering company suggestions for hard valves/seats

#12 Post by desauld » Sun Jan 03, 2021 9:53 pm

Bucket and shims
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Re: Engineering company suggestions for hard valves/seats

#13 Post by desauld » Sun Jan 03, 2021 9:54 pm

Adjustment tool
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Re: Engineering company suggestions for hard valves/seats

#14 Post by desauld » Sun Jan 03, 2021 9:56 pm

Engine internally clean.
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Gilbertd
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Re: Engineering company suggestions for hard valves/seats

#15 Post by Gilbertd » Mon Jan 04, 2021 1:30 am

May be a silly question as I've never worked on one of these engines, but is it possible to slacken off the cam bearing caps so it can be lifted a touch to allow you to remove the shim? Could you get away, even in the short term, with fitting a thinner shim to get the gap back?
96 Saab 900XS, AEB Leo, sold
93 Range Rover 4.2LSE, Lovato LovEco, sold
97 Range Rover 4.0SE, multipoint, sold
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96 Range Rover 4.6HSE Ascot, AEB Leo, my spare


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desauld
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Re: Engineering company suggestions for hard valves/seats

#16 Post by desauld » Mon Jan 04, 2021 10:02 am

Gilbertd wrote:
Mon Jan 04, 2021 1:30 am
May be a silly question as I've never worked on one of these engines, but is it possible to slacken off the cam bearing caps so it can be lifted a touch to allow you to remove the shim? Could you get away, even in the short term, with fitting a thinner shim to get the gap back?
Not a silly question at all. If it was the exhaust side I think I could maybe just about get the cam lifted without disturbing the main timing and have a go at playing with the shims. As it's the intake side that's the side the main timing chain acts on and so I would really need to remove the timing gear, which I have never done before. Almost all my engine experience is on vag engines which are mostly belt driven. If I'm getting into playing with shims and having to remove the cam drive chains it feels right just to pull the heads. I need to chat to a local engineering company I have used for boring blocks etc and see what they reckon with the head reworks.

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Re: Engineering company suggestions for hard valves/seats

#17 Post by Gilbertd » Mon Jan 04, 2021 1:34 pm

I couldn't work out from your pics which was inlet cam and which was the exhaust. I figured it looked to be the one with the main timing chain on it but your pic of the tappet push down thingy seemed to show it as being the one driven by the single chain. I would assume that main chain has a tensioner? Can that be backed off to give a bit of slack on the chain and allow the cam to be lifted slightly?
96 Saab 900XS, AEB Leo, sold
93 Range Rover 4.2LSE, Lovato LovEco, sold
97 Range Rover 4.0SE, multipoint, sold
98 Ex-Police Range Rover 4.0, AEB Leo, daily motor
96 Range Rover 4.6HSE Ascot, AEB Leo, my spare


Proud member of the YCHJCYA2PDTHFH club.

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Re: Engineering company suggestions for hard valves/seats

#18 Post by LPGC » Mon Jan 04, 2021 1:41 pm

I started writing much the same as Gilbert has in post #17, just that it's difficult to imagine much going wrong with the bucket since they're not hydraulic.
Out of interest I had a bit of a read on a few US forums regards your sort of problem on this engine, there's talk of possibility of an engine overheat situation causing valve seats to drop/shift. Probably not something you could easily check for but might be worth a look from both ends of the valve using a borescope and compare to another cylinder.
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Re: Engineering company suggestions for hard valves/seats

#19 Post by Pinger » Mon Jan 04, 2021 4:17 pm

This....
Gilbertd wrote:
Mon Jan 04, 2021 1:34 pm
I couldn't work out from your pics which was inlet cam and which was the exhaust. I figured it looked to be the one with the main timing chain on it but your pic of the tappet push down thingy seemed to show it as being the one driven by the single chain. I would assume that main chain has a tensioner? Can that be backed off to give a bit of slack on the chain and allow the cam to be lifted slightly?
.... and a slight rotation of the cam CW should raise it enough. Chain driving the exhaust cam will possibly restrict you but should be surmountable,

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Re: Engineering company suggestions for hard valves/seats

#20 Post by desauld » Mon Jan 04, 2021 7:26 pm

LPGC wrote:
Mon Jan 04, 2021 1:41 pm
I started writing much the same as Gilbert has in post #17, just that it's difficult to imagine much going wrong with the bucket since they're not hydraulic.
Out of interest I had a bit of a read on a few US forums regards your sort of problem on this engine, there's talk of possibility of an engine overheat situation causing valve seats to drop/shift. Probably not something you could easily check for but might be worth a look from both ends of the valve using a borescope and compare to another cylinder.
Thanks for the comments guys. It may be possible to do what's been suggested but I believe I need the timing cover off to do that, which involves taking all the accessory drives and brackets etc off the front of the engine. Definitely doable, but not a simple job, and if I'm going to do it I suppose I should do it once and do it right.

Do you have a link to the forum thread with the US cars with the similar issues? My car hasn't overhead, or moved above the center mark in my ownership, and I have done about 20k miles in it, now just under 150k total.

It is hard to see how this could of happened, and how it's Lpg related. My local engineering company has also gone bust in November of last year so I have been pointed towards another somewhat local place. He can do hard seats and mentioned by name the ones I linked above, etc so I might give him a go.

I also sent emails to supertech valves and Ferrea valves to see if they stock anything compatible, or would it be a custom job, read expensive.

I called je motor works in Coventry as they used to do lpg conversations on theses including changing seats etc and they confirmed they where happy to do the work, which involve fitting hard race seats, all new factory valves, gasket's, seals, chains etc, and if I left the car in it would cost just a nudge over 7k.. I have asked what it would cost for just the head work. I have a feeling the local guy will get the job.

I want to do a compression test of the other cylinders just so i know what health that bank is in before I get into her. Now, finding time..

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