valve stem, valve guide, rings

mk15mr2 · 12-18-2008, 09:52 PM

Ok so i have an engine that has a new headgasket but smokes at high rpms and when you remove your foot from the gas under engine breaking. I was told it is rings and valve guide seals. Are valve guides and valve stems the same thing? Second question being would it be worth rebuilding?

328FTW · 12-19-2008, 01:26 AM

Rings are the bit that seals the piston to the cylinder walls. The valve guides are seals on the valve stems so no they are not the same thing.

Try a compression test and if that is all good it is valve guides only. It sounds a little like valve guides from the high rpm let off smoke you describe (could be rings as well but the compression test will tell you that). If it is valve guides I wouldn't worry about it unless you fail your road safety inspection (or whatever you call it) because of it. Just keep the oil levels in check and that is about all. Bad guides don't hamper performance you will just get smoke which as long as you don't mind the looks you get from environmentalists you drive past is fine. It is something you do during a rebuild but not something you would really do a rebuild specifically for.

mk15mr2 · 12-19-2008, 10:46 PM

One more question, after the headgasket was replaced (bought the car for 200) we changed the oil approx 100 miles after. it was really dirty. we changed it a second time again really dirty. Is it normal for the oil to get dirty so quickly? like 100 miles or less? I also was told synthetic burns clear. no smoke.

328FTW · 12-19-2008, 11:24 PM

It is unusual for oil to be dirty that quick. I would say the previous owner didn't change the oil regularly and their is gunk throughout the oil system that is getting washed into the new oil. I would get some seafoam and some cheaper grade oil and put it in the oil to clean the engine out then go full synthetic once it is cleaned out. And synthetic burns blue like any other oil it is not clear burning or anything.

tjmr2 · 12-22-2008, 01:10 AM

The head has valve guides and valve seals.

The valve slides up and down inside the valve guides and the tolerance between them and the guide is critical. Too much clearance and the valve won't seat properly, can wear your valve and seat = bad juju.

The valve seal sits on top of the valve guide in the head, and seals the intake manifold vacuum or exhaust manifold pressures from the oil gallery of the head. The seal hides under the shim and bucket so you have to take the cams out to see them.

A bad valve seal can allow combustion gasses into the crankcase, or place a large vacuum on the crankcase, thus looking like massive ring blow by accompanied by dirty oil and high oil consumption. Good for killing mosquitoes, bad for cool factor if your girl friend is following you.

I had 1 bad intake valve seal. Started off with a small puff of smoke at high RPM, like 2nd to 3rd. 10k miles later I was blowing through a quart of oil in 120 miles.

Tore that engine down to pieces, thinking I had a bad ring. All I found was the bad intake seal and some damage to the valves and seats from the excessive carbon. That's how I ended up with my Black Top.

Run a leak down test to determine the problem. It's an inexpensive tool to make and while a pain to do in the car it will tell you where the problem lies before you start tearing everything apart and spending money. Here is a link, you can google more.

Building and Using a Cylinder Leakdown Tester

Just my 2 cents worth, all too often people look at an immediate problem and are only willing to spend money to fix it. They are in a hurry, and to pay the mechanic more than is necessary seems like a waste of money. Personally if I pull the head thinking I've got a bad head gasket I'm also checking all valves, valve guides, and installing new seals everywhere in the head. If I spend a couple of hours and maybe another hundred dollars in seals and don't have to go back into an engine to replace a seal that I could have replaced six months ago it's money and time in the bank.

Guess what I'm saying is spend the extra money and do the job right the first time. Costs you less in the long run.

Good luck.

mk15mr2 · 12-22-2008, 09:16 PM

so i did a compression test. 60psi, 120, 130, 150. 4-1 what the heck does that mean. head gasket was replaced. anyway we were thinking of just getting a blacktop cause to buy a whole gasket and seal kit, possibly rings would be expensive. although it would be a nice learning experience and i could sell a fully rebuilt engine to someone who needed it. i would do it right. proper torque specs and pattern. testing the deck for flatness. all that crap.

328FTW · 12-23-2008, 06:08 AM

Do you still have the compression tester cause I would recheck that 60psi cylinder making sure you have the throttle wide open and if is the same then put a couple spoonfuls of oil in it and if it comes right back up then that ring is stuffed. If I remember right under 140psi means you need rings. Might be your chance to get some engine building experience.

Blacktop will up the hp a lot if you do that swap. mr220v on here can help you out with the wiring harness and the rest is basic mechanics.

mk15mr2 · 12-23-2008, 09:55 AM

yup it is the rings. i will do the blacktop swap and rebuild the other one for his mr2. his is getting a little slow these days.

12-18-2008, 09:52 PM	#1 (permalink)
mk15mr2 No Skills Join Date: Dec 2008 Location: Arizona Posts: 36 Thanks: 10 Thanked 0 Times in 0 Posts iTrader Rating: (1/100% )	valve stem, valve guide, rings Ok so i have an engine that has a new headgasket but smokes at high rpms and when you remove your foot from the gas under engine breaking. I was told it is rings and valve guide seals. Are valve guides and valve stems the same thing? Second question being would it be worth rebuilding?

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12-19-2008, 01:26 AM	#2 (permalink)
328FTW 3vzfe tinkering Join Date: Aug 2008 Location: New Zealand Posts: 1,537 Thanks: 12 Thanked 100 Times in 84 Posts My Google Map iTrader Rating: (0/0% )	Rings are the bit that seals the piston to the cylinder walls. The valve guides are seals on the valve stems so no they are not the same thing. Try a compression test and if that is all good it is valve guides only. It sounds a little like valve guides from the high rpm let off smoke you describe (could be rings as well but the compression test will tell you that). If it is valve guides I wouldn't worry about it unless you fail your road safety inspection (or whatever you call it) because of it. Just keep the oil levels in check and that is about all. Bad guides don't hamper performance you will just get smoke which as long as you don't mind the looks you get from environmentalists you drive past is fine. It is something you do during a rebuild but not something you would really do a rebuild specifically for.

12-19-2008, 10:46 PM	#3 (permalink)
mk15mr2 No Skills Join Date: Dec 2008 Location: Arizona Posts: 36 Thanks: 10 Thanked 0 Times in 0 Posts iTrader Rating: (1/100% )	One more question, after the headgasket was replaced (bought the car for 200) we changed the oil approx 100 miles after. it was really dirty. we changed it a second time again really dirty. Is it normal for the oil to get dirty so quickly? like 100 miles or less? I also was told synthetic burns clear. no smoke.

12-19-2008, 11:24 PM	#4 (permalink)
328FTW 3vzfe tinkering Join Date: Aug 2008 Location: New Zealand Posts: 1,537 Thanks: 12 Thanked 100 Times in 84 Posts My Google Map iTrader Rating: (0/0% )	It is unusual for oil to be dirty that quick. I would say the previous owner didn't change the oil regularly and their is gunk throughout the oil system that is getting washed into the new oil. I would get some seafoam and some cheaper grade oil and put it in the oil to clean the engine out then go full synthetic once it is cleaned out. And synthetic burns blue like any other oil it is not clear burning or anything.

12-22-2008, 01:10 AM	#5 (permalink)
tjmr2 Cage Fighter Join Date: Jan 2008 Location: Colorado Posts: 310 Thanks: 0 Thanked 49 Times in 46 Posts My Google Map iTrader Rating: (0/0% )	The head has valve guides and valve seals. The valve slides up and down inside the valve guides and the tolerance between them and the guide is critical. Too much clearance and the valve won't seat properly, can wear your valve and seat = bad juju. The valve seal sits on top of the valve guide in the head, and seals the intake manifold vacuum or exhaust manifold pressures from the oil gallery of the head. The seal hides under the shim and bucket so you have to take the cams out to see them. A bad valve seal can allow combustion gasses into the crankcase, or place a large vacuum on the crankcase, thus looking like massive ring blow by accompanied by dirty oil and high oil consumption. Good for killing mosquitoes, bad for cool factor if your girl friend is following you. I had 1 bad intake valve seal. Started off with a small puff of smoke at high RPM, like 2nd to 3rd. 10k miles later I was blowing through a quart of oil in 120 miles. Tore that engine down to pieces, thinking I had a bad ring. All I found was the bad intake seal and some damage to the valves and seats from the excessive carbon. That's how I ended up with my Black Top. Run a leak down test to determine the problem. It's an inexpensive tool to make and while a pain to do in the car it will tell you where the problem lies before you start tearing everything apart and spending money. Here is a link, you can google more. Building and Using a Cylinder Leakdown Tester Just my 2 cents worth, all too often people look at an immediate problem and are only willing to spend money to fix it. They are in a hurry, and to pay the mechanic more than is necessary seems like a waste of money. Personally if I pull the head thinking I've got a bad head gasket I'm also checking all valves, valve guides, and installing new seals everywhere in the head. If I spend a couple of hours and maybe another hundred dollars in seals and don't have to go back into an engine to replace a seal that I could have replaced six months ago it's money and time in the bank. Guess what I'm saying is spend the extra money and do the job right the first time. Costs you less in the long run. Good luck.

12-22-2008, 09:16 PM	#6 (permalink)
mk15mr2 No Skills Join Date: Dec 2008 Location: Arizona Posts: 36 Thanks: 10 Thanked 0 Times in 0 Posts iTrader Rating: (1/100% )	so i did a compression test. 60psi, 120, 130, 150. 4-1 what the heck does that mean. head gasket was replaced. anyway we were thinking of just getting a blacktop cause to buy a whole gasket and seal kit, possibly rings would be expensive. although it would be a nice learning experience and i could sell a fully rebuilt engine to someone who needed it. i would do it right. proper torque specs and pattern. testing the deck for flatness. all that crap.

12-23-2008, 06:08 AM	#7 (permalink)
328FTW 3vzfe tinkering Join Date: Aug 2008 Location: New Zealand Posts: 1,537 Thanks: 12 Thanked 100 Times in 84 Posts My Google Map iTrader Rating: (0/0% )	Do you still have the compression tester cause I would recheck that 60psi cylinder making sure you have the throttle wide open and if is the same then put a couple spoonfuls of oil in it and if it comes right back up then that ring is stuffed. If I remember right under 140psi means you need rings. Might be your chance to get some engine building experience. Blacktop will up the hp a lot if you do that swap. mr220v on here can help you out with the wiring harness and the rest is basic mechanics.

12-23-2008, 09:55 AM	#8 (permalink)
mk15mr2 No Skills Join Date: Dec 2008 Location: Arizona Posts: 36 Thanks: 10 Thanked 0 Times in 0 Posts iTrader Rating: (1/100% )	yup it is the rings. i will do the blacktop swap and rebuild the other one for his mr2. his is getting a little slow these days.