YEG_2002

Weigh In, replacing valve guides

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Hello Everyone!

 

Long time lurker, not a frequent poster.

I have a conundrum with my head. I removed the e12 head from my 74 2002 because it was smoking on the deceleration. 

I was told by the previous owner that the head was rebuilt. 

Its extremely clean on the inside, but just as suspected there was a couple of valve seals that were bad.

 

Now as i understand it, im suppose to replace the valve guides with upgraded later versions. The upgraded being 50mm in length and the early being 52mm.

 

Mine do measure in at 50mm, and the valves have little play left to right. 

 

I believe what casued the issue was running the car on the wrong oil. There was an oil sticker on the windsheild that read 5w30 so i assume that the owner ran the wrong oild for the life of that rebuild. 

 

Is there any visual signs to tell if the guides are indeed upgraded or the seals as well. And would you replace the valve guides regardless? 

 

I appreciate the input very much, heres a picture of my car. 

 

18198240_10155256392371310_7169325764639396854_n.jpg

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The new guides have a turned- down neck at the top, and a smaller seal fits over them.

 

The earlier ones are pretty straight. (no- one sells them anymore, so I have no pix)

 

If yours are well within tolerance (you have to measure 4 ways from next week,

as their wear mode is to ovalize) a new set of whichever stem seals fit your stems will do it.

 

The later stem seals ARE better, but not better enough to change out good guides for.

 

hth

 

t

 

early seal.jpg

late guide.jpg

late seal.jpg

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Thanks so much for the reply TobyB 

 

To make ensure i dont mess this up, ill have the machine shop measure the valve guides with the valves and they can let me know if they should be replaced

 

The guides in my head dont look like the picture you posted, but the seals i removed do. So i have attached a picture of both the guide and seal. 

 

 

 

guide.jpg

seal.jpg

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Those seals look like the old ones Toby's talking about. Hard to tell 'cause it's damaged.Your guides look different because they haven't been turned down yet (with a little tool that fits in your drill) so you can use the newer small seals that either have a teflon ring inside or are made completely of white plastic with a metal band. Either kind of new seal are a vast improvement over the old hard black rubber ones you took off. Any machine shop will tell you on the spot if you need guides. If you have a couple of tools and you're that kind of guy, you can change guides at home. If there's nothing else wrong and the guides are good, I'd cut down the guides, install new style seals and get back together. For sure the seals were making the smoke.

Edited by andyleonard

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FWIW, the guides are really easy to replace and I would have the machine shop just replace them. They are quite affordable from blunt. For kicks and giggles I actually put my head in the oven and knocked my old guides out myself, but had the machine shop install the new ones. What's your budget, anyways? I think i paid <$100 for the new guides and machine shop pressing them in. Extra for the valves to be lapped and seats ground, which im guessing you do not have to do.

 

In my mind, $100 is worth the peace of mind if you're already in there.. which, judging from your picture, you are already in there. :) 

 

But im probably the least experienced person here... I just would not want to have to take apart my head again in 20k miles because I didn't pay the $100 now...

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For the cost, your better off replacing the guides now and just do the job right the first time.

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So what you have there are the very old style stem seals.  They still come in one

or another of the (otherwise good) head gasket kits.  

 

They don't work very well, by modern standards.

 

So if you replace the stem seals with the modern design 'old style' seals, you'll cut your valve 

oil consumption a lot.  Probably almost exactly as much as by switching guides.

 

Every time the guides get whacked out, the head distorts a little.  By design.

And you then should at least lap the valves to make sure they're still centered,

which they usually, but not always, are.

So if your guides are worn out, or marginal, by all means replace them.

But if they measure fine, put new style old design seals on and be done with it.

 

 

t

 

 

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Thanks for all the input everyone. This has cleared up all of my suspicions. Im going to take the head to the machine shop, see what they say and then go from there. If they measure the guides and say they are perfect, ill replace the seals, have the valves lapped and the head hot tanked and decked.

If the guides are indeed a worn or bad, ill have them replaced of course with the new style. 

 

Thanks again everyone 

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Sounds like a plan.  But I'd ONLY have the valves touched up if the shop says they need it

(they will most likely say so)

and likewise, only surface the head if it needs it.  They don't make these things

anymore, and you can't cut them thicker...  ;)

 

t

 

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3 hours ago, TobyB said:

They don't make these things

anymore, and you can't cut them thicker..

You mean to say they can't 3d print a new layer on the bottom!:rolleyes:

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I guess I am in the minority when it comes to valve stem seals.  The old "viton" seals, that I believe are still available new, have served me well for decades - without any significant issues. The newer style work equally well; however, I have been told that these newer/softer versions are less forgiving in the event of oil starvation.  I mention this only because a machinist once gratuitously volunteered it and showed me his collection of new looking but worn seals.  Although fortunately not a common occurrence, stem seals have been known to tear due to improper installation or work loose.  In that rare situation, the fix could be as simple as installation of a new seal.  Whatever your choice, something to bear in mind is the fact that valves may be long lived but they are not impervious to stem wear.  Any good machinist would check for stem wear when guide replacement is indicated - for presumably obvious reasons.

 

The assumption that the wrong viscosity oil led to abnormal seal and guide wear may not have been as much of a problem as dry starts, low oil pressure or dirty/contaminated oil.  If your theory were accurate and the wrong oil led to premature valve guide wear, the same logic would not paint a prettier picture for the business parts in the lower end of the engine.

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2 hours ago, jimk said:

You mean to say they can't 3d print a new layer on the bottom!:rolleyes:

 

 

I cut it off twice and it's still too short!

 

:D

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Wanted to update this thread with the results!

After visiting what seemed like all the machinist shops in Clagary, i had the same conclusion from all of them

 

The valve guides were worn but could be made do with, and all the intake valves needed replacement as well as the seals. 

 

I went ahead and ordered all new style guides, new style seals, and intake valves from ireland 

 

Head is now rebuilt and looks brand new, very pleased with the work. For anyone in the calgary area, precise engine builders did the work. Paid 450 for all the work and other shops were quoting well into the $700 mark. Now i need to finish painting the engine bay and put this little m10 back togethter 

 

Thanks for the help 

newguides.jpg

thumbnail.jpg

Edited by YEG_2002

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A quick, perhaps trivial note regarding your worry about 5w 30 oil being used in your engine:

 

At the shops where I've worked, we put oil change stickers on the windshields of customer cars, just as a reminder for them to get their next oil change in a timely fashion. Since the vast majority of modern cars run 5w30 oil, the companies that supply these stickers (Castrol, Mobil, whatever - we get giant rolls of them from our vendors) will usually have "5w30" pre-printed on them all. On some cars, I'll take a sharpie and cross out the 5w30 and write in the proper viscosity used in the last oil change. (on my own car, I just take a sharpie and write on the windshield, my last oil change...it's a habit of mine - wipes off easy 3500 miles later)

 

So - your car might have had nothing but pure brad Penn 15/40 in it for dozens of oil changes, but the decal doesn't say so. If it's hand written "5w30"....then I might be worried. :) That stuff would pour out of the engine / rings / seals like shit through a goose. 

 

 

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