Valve Guide Advice

[Telf 224 2 Cars]

Hi all,

 

This weekend I'm helping a friend replace a set of valve stem seals. Ive done the job before but it was about 10 years ago. Ive read through my workshop manual and it all seems straight forward but he keeps harping on about his valve guides possibly being worn.

 

Now as far as I can remember when I stripped the head on mine a (decade ago!) I just removed the stems consisting of the spring, collet and seal. I don't remember there being a guide.

 

Does the guide hes referring to screw into the head and I just didn't notice it? If so are the difficult to change?

 

Any help would be great

 

Oh I forgot to say its a 1.9 head we are working on

 

 

Thanks

Edited April 10, 2014 by Telf

[GilesW 41]

Valve guides are the tubes the valve goes through in the head. Over time they can get worn and then need replacing to ensure the valve is held true.

[GilesW 41]

If they are like the Vauxhall heads (in sure they are) the it's a proper engine machinist job to change as it'll involve heating the head, pulling out the old and inserting new again making sure they're true and to the right depth.

[Telf 224 2 Cars]

Hi,

 

Ok well I guess I missed them when I last replaced the seals- so do they unscrew from the head or do they require any special tooling- ive been flicking through the Haynes manual but cant find a reference to them!

 

Thanks

Edited April 10, 2014 by Telf

[Telf 224 2 Cars]

I suppose that when its stripped sunday we will just have to have a look and see what state they are in, problem being that the car is a regular runner so it cant be off the road for more than afew days

 

I'll report back with my findings!

[Normski 1]

The guides are a press fit into the head, not really a diy job, so that's why it's not in the haynes.

[mrfirepro 127 1 Cars]

Haynes manual says...

 

Check the valve guides for wear by inserting the relevant valve, and checking for side-to-side motion of the valve. A very small amount of movement is acceptable. If the movement seems excessive, remove the valve. Measure the valve stem diameter, and renew the valve if it is worn. If the valve stem is not worn, the wear must be in the valve guide, and the guide must be renewed. The renewal of valve guides is best carried out by a Peugeot dealer or engine overhaul specialist, who will have the necessary tools available.

[Tom Fenton 1,542]

The guides are pressed in, the thing is that due to tolerances when new ones are pressed in they must be reamed to size, then the valve seats need to be re cut to the new guide. It is a job for an engine machine shop. Also the cam followers will also need to be re shimmed afterwards which could be done at home but it's much easier to let the machine shop do it as generally they will either have shims in stock or can surface grind the old ones to suit.

[Telf 224 2 Cars]

Hi guys,

So we stripped the head today. Managed to snap a head bolt in the process but never mind.

With the valves released gave each on a wiggle and there's no excessive play so I guess there ok.

Valve seals absolutely solid from age.

once the heads skimmed and ready to rebuild is it necessary to remeasure the valve clearences or just reuse the old shims.

My bud who's car it is doesn't seem too keen on messing with the valve clearance but I imagine they will have altered with wear?

Thanks for the advice much appriciated

[jdt 6]

it would make sense to lap the valves in while you have it in bits and then check all the valve clearances - they will not be far out, measure the shims while it is in bits then when you check the clearance you can calculate what shim you need.

[DamirGTI 342]

Just the head skim wont have any effect on valve clearances .. providing that you do not mix present fitment position of each shim , so when dismantling group and pack each valve with it's shim and lifter and upon assembly fit back on the head as it was before .

But do check the clearances anyway after the assembly just to be sure that you didn't mix up any of them shims by mistake , and generally in order to check that it's all fine with the clearances before finishing the engine ready for the start up .

 

If re-cutting valve seats or lapping the seats , replacing/renewing or mixing the valves , these will change the clearance thus you'll need to measure and readjust the clearances as needed .

Re-cutting or just lapping the seats will always make the clearance tighter , by machine re-cutting them a little bit more so you might need an set of different shims but by usual lapping with fine grinding paste (if the seats are in reasonably good/serviceable state and thus that no "aggressive lapping" with coarse grinding paste isn't needed) the clearances will close just a little bit so old shims can be reused and hand regrinded up to the required thickness for bringing the clearance back as specified .

 

I did this "hand shim regrind" a lot of time before and continue to use this method still today when ever i need to , after lapping the valves .. it's really easy and pretty quick too , all you need is a few sheets of 500grt and 800grt sanding papers , some 2 stroke oil (or any other oil will do ..) and of course an micrometer and feeler gauges , and some elbow grease !

Measure the clearances first , then calculate how much you need to take off the each shim to get the desired clearance . Then , before you start grinding the shims need to identify the top and bottom sides of the shim - top side has slightly chamfered edge and bottom side has sharp edge (can be distinguished visually , if not then by finger/nail pass round the shim edge you'll feel the difference between chamfered vs sharp shim edge) , when you figure out which side is which pick the side with the sharp edge cos you'll be doing the grinding on that side of the shim . The side with the sharp edge goes first ie. on the actual valve stem whilst the other side with chamfered edge must be on top faced opposite of the valve stem ie. it's the valve lifter contact side .

 

Tape an sheet of 500grt sanding paper on an nice flat board , lube the paper with some oil (not too much ! cos you'll be more "gliding" on the paper then removing metal from the shim surface) , pace the shim with the said side on the paper , grab it with fingers , press lightly and start grinding/turning the shim in circular motion .. do the grinding/turning for say 20sec. then stop , clean up the shim and measure it with multimeter and note how much you've taken off of it during that 20sec. , and perform as explained until you're almost up to the desired shim thickness then - switch the sanding paper for finer 800grt and do just a few seconds final grinding/turning in order to smooth up the surface . Clean up thoroughly free from any metal particles an fit on the head .. and check the clearances ... if needed repeat the process for fine clearance adjustment .

 

I'd also recommend doing this "hand grinding" for the valve lifters as well .. as nowadays when they're such old all of them will have more or less worn top surface (slightly dished because of the camshaft lobe passes) , and this can and will trick you when measuring clearances with feeler gauges - if the top lifter surface isn't true as it supposed to be . So , i first resurface the lifters and then do the clearance measuring and adjusting .

The procedure for the lifters is the same as the one above for the shims grinding - 500grt paper first , lube it lightly , grab the lifter with fingers with top side facing down against the sanding paper press and swing in circular motion .. stop periodically and clean the top side - what you'll see after say first 30 seconds of grinding will be partially grey top surface with kinda glazed silver specks around the center , like crazing marks - do the grinding until this marks disappear and entire top surface of the lifter turns grey , then switch to 800grt paper do few more rounds and finally can even end them with 1000grt paper if you want super fine finish , me i just smooth them with grey scothcbrite pad after the 800grt paper . (theres quite a lot of material on the lifters so theres no danger doing this what so ever)

 

The result will be whisper quiet engine (providing that you do the valve clearances good as well) , reduced lifter/cam lobes wear and more accurate valve clearances ...

 

For valve clearance measuring and adjusting - do this always after the head is fitted onto the block and all the head bolts are torqued down to the specs. . Adjusting the clearances with the head removed on the bench will not be accurate cos when the head is fitted onto the block and all the bolts torqued to the final stage , the head bolt torque force will "squash" the head a bit thus the clearances on all the valves will close from 0.05mm up to 0.10/12mm .

 

Clearances , i usually set them like so : 0.15mm inlet - 0.30/35mm exhaust .

 

 

D

Edited April 10, 2014 by DamirGTI

[Telf 224 2 Cars]

Hi ,

 

Thanks very much everybody for your advice. At the moment the head is off being skimmed as I said. The guy who it belongs to has used grinding paste to remove all the carbon etc from the valves so they look nice a smooth again.

 

The head is being aqua cleaned so I imagine that the valve seats will be clean but aren't being machined or recut in any way.

 

I will get him to grind the top of the tappet too.

 

I'm a little confused still about the clearance of the valves. Indulge me a moment! In my own words I will type what I think I need to do!

 

I basically need to rebuild the head and bolt it all back down to its final torque- once that's done manually crank the engine so each lobe of the cam is pointing upwards and measure the clearance. Then make up the difference with an additional shim to the values you stated.

 

I hope that's correct and Im not being ultra stupid!

 

Thanks very much

 

P

Edited April 11, 2014 by Telf

[welshpug 1,661]

You got it spot on, nearly, you don't add extra shims, you change them for thicker/thinner ones.

[DamirGTI 342]

If the clearance ends up a bit on a tight side , you can easily thin the shims down just by hand regrinding them .. grinding them say roughly 30sec you'll be taking around 0.05mm of the original shim thickness , so if you're patient and proceed with the grinding little longer can thin them down quite a bit and make really precise thickness of the each individual shim based on how much you need to obtain desired clearance .

 

Otherwise , if the measured clearance is too big , you'll need to find thicker shims .. but first , measure all of them with micrometer and see if you can bring the clearance up or near the specs. by mix them .. so that you don't necessarily need entire set of all 8 different shim thickness , say you get 4/5 valves up to the specs. by mixing the shims then you'll need to find just 3/4 additional different shims for the rest of the valves .

 

For inlet don't go lower than 0.15mm nor bigger than 0.25mm , exhaust no more than 0.30mm as an low value or 0.45mm bigger (lower than this values can end up burning up the valves and will make engine running rough at idle and off idle from low to mid revs , bigger will make the engine very noisy with decrease in engine performance/acceleration and in the long run valve lifter and camshaft lobe will start to wear more rapidly)

 

D

[Telf 224 2 Cars]

Ok, should hopefully get the head back tomorrow. Atm still working on removing the sheared bolt which is proving a pain.

 

Ill report any further developments as they occur!

 

Cheers

[Telf 224 2 Cars]

Hi all.

This is turning into a bit of a saga now!- the heads now rebuilt and ready to go back on but the head bolts still not sorted

 

Its snapped at the top of the thread so basically the last 2 inch portion is still in the block. The guy who it belongs to has had someone come and try to extract it but from what I saw yesterday has made a bit of a mess.

 

The bolts been drilled through(its the forward centre bolt) so you can see daylight but its not vertical and to me looks like its already damaged the thread in the block.

 

As I see it the only real option is to drill the whole lot out and helicoil it. I'm no expert at this so I'm wondering does anybody know what size of tap/helicoil etc is required for the bolt?

 

Failing that I thought maybe putting a shorter bolt in- I think I've read somewhere that the 205 diesel headbolts are shorter so I thought maybe just helicoil above the remains of the ruined bolt- or use a spacer on the existing length bolt?

 

Thanks

 

P

[Tom Fenton 1,542]

I have typed a similar method on here before but this is what you need to do.

Get a decent piece of steel plate and using a couple of old head bolts and some tube spacers bolt it to the top of the block. Then you need to get hold of a magnetic mount drill sometimes known as a rotabroach. This will allow you to carefull drill out the broken bolt and get it square to the top face.

Then you need a helicoil kit thread 11x1.5 and it needs to be the double length inserts to give enough thread length.

Drill to the helicoil size, tap the hole install the helicoil, job done.

I have done this a couple of times now.

A shorter bolt will not work, you need the full thread engagement in the alloy block otherwise you will just pull the thread out before you get the bolt tight enough.

[Telf 224 2 Cars]

Hi Tom

 

Thanks for the advice- I don't think getting hold of a rotabroach is going to be a viable option, good to know what size thread it is and that a short bolt is not an option

 

P

[Tom Fenton 1,542]

You can hire them from the various tool hire places as steel erectors often use them to drill girders etc in situ.

[Telf 224 2 Cars]

Ah yeah Ive just seen them £20 a week- that's maybe an option

 

thanks

[jackherer 543]

I think I know the owner of this engine, I can't remember his name but if it's the same person he came round mine yesterday in a black 306 looking for an oil spray bar end cap?

[Telf 224 2 Cars]

Yes mate,

 

Its the same person- I was putting head back together yesterday - cleaning the spray bar and noticed a nice crack down the middle!

 

P

[jackherer 543]

I don't have any 8Vs so I gave him an MI16 one, it looked the same but it's worth checking it seals properly.

[Telf 224 2 Cars]

Update!

 

Bit of a disaster- owner tried to drill the bolt out himself but has written off the head! He took the block to an engineering place this morning who confirmed it wouldn't be possible to helicoil it.

 

So now we are fitting a replacement engine that a local guy sold for £100.

 

The mission continues!

P

[Telf 224 2 Cars]

Update of an update,

 

The replacement engine also now has a snapped head bolt- same one front center. Guy in the garage snapped it taking the head off prior to selling it. Luckily he has another 1.9 block with the head already off- so that's getting fitted instead.

 

Hopefully it will be done by tomorrow! maybe hopefully!

 

P