Replacing The Valve Seals While Keeping The Cylinder Head On
25 replies to this topic
Posted 2008-06-21 17:05:47
I have previously told you about my problems with Abnormal Oil Consumption, and i thought i would continue the story now.
I went back to the place where i repaired my car to see if i would get anything out of the warranty since the car still consumed quite a lot of oil.
I told them that the car would consume more oil on one long trip then a number of shorter trips over a few days. They then recommended me to change the oil and see how the problem would develop over a few thousand kilometers. So i asked them "What about the possible leak at the valve seals?", and why didn't you change them while the cylinder head was off? They answered me that they thought they were ok, and that they could replace them later without removing the cylinder head if the leak remained.
A few thousand kilometers later i returned to ask them to replace the valve seals as the car would rather consume more and more oil. They then told me that they could only change the valve seals if the cylinder head was off!
I went back home to start to research about this in the internet, but stopped at another place to check if their capabilities were better.
They said that it would be no problem at all to replace the seals, and that they had done that several times before. By now i was confused, so i asked them how they would do it. They told me how they would just lift the cam off, replace all the seals, and put it all together again.
Well back at home, i lifted off the cover to have a look at the cam. It would definitely not work to lift off the cam, because the cam is fitted with the same bolts as the cylinder head! So, i put it all together and went to research about this.
I found out about spring compressors and how to use them to replace valve seals. I thought this would be the way to go, but i went everywhere without finding a shop selling them.
I went back home and decided to design a spring compressor on my own. I then went to my friend's workshop to have it manufactured.
I went home to try the spring compressor when i finally got it from the workshop. It all seamed to work after a little bit of tweaking at home, so i went back to the place where they repaired the car in the first place to see if they now thought they could do it.
They wanted to give it a try, so they opened up the cover. A while later they gave up and told me that my tool was not working.
A while later, one of the guys came back to my car and put the cooling water on the floor, and another guy appeared at the cylinder head. I asked him what he was going to do, and he replied that he would take the cam off.
I was prepared to tell them to put my engine together again, but i told the guy not to continue and went to have chat with the manager.
I told the manager that i was very confident that my tool would do the job, and asked him if i could help him with the springs and let him do the rest of the job. He thought about it for a while before he told me that i could go ahead.
He was suspiciously "around" as i removed the first spring. After that he replaced the seal, and i put the spring back.
I tried to involve him more and more, as i proceeded with the other valves, and tried to teach him how to use the tool as well. I think he appreciated to get involved, because he got more and more interested to continue after every valve we finished.
He told me to start the car when it was all put together again, and then he went to the exhaust pipe. I speeded up the engine a few times before he came back to tell me that i don't have any oil leaks at the cylinders anymore. I asked him how he would know that, and he told me that he could tell it from the smell from the combustions.
What do you think about this? Could this be the end of the problem, or is the leak more likely to be elsewhere?
Posted 2008-06-21 21:41:19
Firstly, when you have black smoke coming out the tail pipe continually (worn piston rings/bores etc)
but if it`s the valve stem seals in usually is more evident when changing gear, have someone follow you up a sloping hill (easy to see oil/fumes when under load)..
I changed my stem seals every year on my old 5.7ltr chevy comp ski boat, by making a flat bar with a 2 holes ( 1 hole to bolt the bar onto the rocker post, and the other hole to fish out the collets while levering down the spring with the flat bar )ensure you turn the engine by hand until piston at tdc to avoid losing the valve down into the cylinder bore.....
Posted 2008-06-22 00:52:17
Black smoke from an exhaust pipe usually means a "rich" mixture & NOT any oil burning problem.
If the valve stem seals are leaky, you will usually see a puff of BLUE smoke at engine startup. The smoke will clear after a few seconds of running.
Please bear in mind that some engines consume oil "normally". I had a 1984 Holden Commodore 2150 Blue motor (in Australia), which consumed 1 litre of oil every 2 weeks without fail. Compression tests proved that the engine was ok.
Talking about compression tests, you may request a "wet" & a "dry" compression test. If all is well, both tests will yield the same results, as long as the compression is within vehicle specifications.
If the "dry" results are low compared to the "wet" results, rings may be the problem. If the compression is too low for both "wet" & "dry" tests, valve stem seals &/or head gasket problems may be the cause.
If an engine burns oil, BLUE smoke is usually the result....not BLACK smoke.
Edited by elkangorito, 2008-06-22 00:55:04.
Posted 2008-06-22 01:04:26
On a lot of OHC fords and Vauxhalls in the UK, id take the spark plugs out, feed some good nylon cord into the cylinder, turn over engine by hand till it locks, then remove the springs ect, sometimes it is nesacerary to give the collett ring a sharp blow to release the colletts, the cord would cushion this from the piston and prevent bending of valve or damage to piston, while the spring is off, move the valve stem sideways to check for side float, what type of seal do you have, does it go over the top of the valve guide or is it a rubber o-ring? if its the former, HMP grease can he put inside the cover, this will hold up oil consumption for a while.
Normally engines with this problem will give out a cloud of blue smoke on warm start-up,
Also if i remember your last post about oil consuption, you said that they fitted new piston rings but never glaze-busted [honed ] the bores, they didnt need it? ok, i agree if measured correctly or you can still see [hard to explain] honing marks in the lower bore,
BUT they do need to hone the top of the bore where the rings dont reach, and im sure you will understand this, the top part is original size and will have carbon deposits on it, the new rings are original size and no ring clamp will make them small enough to go past this area without damage, i would think that one or more of the new piston rings is broken, How is the engine breather system? does it lead into the air filter, is it clean, no traces of oil ect?
Simple test for compressions, take out the spark plugs and if possible, put your thumb over the hole while somebody cranks the engine, good compression will lift off your thumb, bad will not move it, so you can pin-point the cylinder, or even start engine, and on idle, with insulated pliers, remove and replace plug leads, listen to engine note change,
Now tell me its a diesel!!!!
Posted 2008-06-22 01:28:43
Thanks for reminding me Lickey.
I believe that the vehicle in question is 2nd hand & old. In hindsight, it would've been best to have the engine reconditioned, which would have involved;
1] polishing the crank or replacing it.
2] replacing both the little & big end bearings.
3] honing or boring the cylinders as required.
4] replacing the valves if needed.
5] reseating the valves (in any case).
6] replacing the pistons & rings.
7] checking the compression & thence replacing valve stem seals as required.
8] priming the oil journals of all bearings.
It appears to me that this would be a solution to the OP's problem instead of taking his car to 72 "mechanics". Of course, one assumes that the OP is able to tell if this work has been done or not.
Nonetheless, the same situation exists in most other countries...the customer either believes the mechanic or does not believe the mechanic. You can't win unless you are mechanically adept or you have a trustworthy mechanic.
Edited by elkangorito, 2008-06-22 01:31:56.
Posted 2008-06-22 16:03:36
Thank you, all of you, for your comments and suggestions!
What is strange with my car is that it has never shown any black or blue or whatever-else-color smoke. At the place where i do some of my repairs (i have only this very one place to go to that i consider "quite good", so either i go there or do it myself), they have told me that they could smell the combusted oil coming out of the exhaust pipe; and that and the fact that the oil was disappearing were the only signs of leaks that i've got. I've even been behind the car while someone else were driving, but no abnormal smoke (hardly any visible smoke at all, in fact).
In the beginning when i had this car it used to be a bit difficult to start in the morning, and later on when i installed an LPG system i also got big problems because the engine wouldn't be possible to tune to run smoothly on gas. I therefore fitted an electronic ignition driver, and the engine immediately started to run smoothly and it also got much easier to start in the morning.
What is interesting with the engine now, after changing the seals, is that the engine fires up instantly! I just turn the key to crank the engine for a fraction of a second; and by then it's already running! I have never ever seen a car that is this easy to start. Even in the morning is starts instantly, possibly a few fractions of a second later compared to when the engine is already warm.
I've also taken out the spark plug that used to be covered with a hard black skin of burned oil, and it's not like that any more. It also seams to be changing it's color to white or gray, or something like that. What color should the spark plugs be for a car that is running properly on LPG, anyway?
I'm not yet running around ringing bells while wearing my party hat, but those two signs of improvement are quite significant, aren't they?
Posted 2008-06-26 18:21:00
As you know there are many reasons for consumption of oil but 1l every 2500kms is not "excessive" if you consider that most people change their oil every 3-5000miles or 5 - 8000kms then your 1l every 2500 kms means your oil is changed every 10000kms , roughly.
One thing you haven't mentioned unless I missed it is the viscosity of oil you are using or if you have changed to fully synthetic oil. If not already using it change to 20 / 50 and don't use 10 / 40. If you are already using 20/50 or the change doesn't have the desired effect bung in a can of STP (Blue can) costs about 135 - 140 baht at Tesco.
I also noticed you are using LPG. Do you have one of those little plastic bottles (900-1500 baht) attached to the vacuum system that feed miniscule amount of oil into the engine to oversome the fact that LPG is a "dry" fuel and does not lubricate the valve stems. BKK taxi drivers us 2-stroke oil, I'm using diesel fuel. Sorry I don't know which has the greater calorific value. The "bottle" adds "oil" at 1000:1 or 500ml every 5000km
Posted 2008-06-29 10:48:27
I would like to see pics of the tool you made to do this job. Thanks
Posted 2008-07-03 20:51:01
I don't have any pictures of the tool i made, and i left it at the repair place for the mechanics to borrow. The tool i used as an inspiration is available for display here:
My tool is more narrow and does not require as much space as the tool in the picture, but the idea is the same.
Posted 2008-07-03 23:28:41
I think that any abnormal consumption is also means it's "excessive", but otherwise i suppose it could be ok under the right circumstances...
I'm using 15W/40. What is that STP stuff good for? I mean, what does it do to the engine? Are there negative side effects to use it?
That lubricator for LPG vehicles is interesting? Where in Thailand can i buy it?
There is no way i will fill it with two stroke oil and make my car smell like a bloody TukTuk, but i suppose there are other lubricants available (perhaps at 10-15bath/10000km more than the 2-stroke oil) for it?
Posted 2008-07-04 22:03:25
That maybe right on a lawn-mower engine but not so good on a car engine! Use a screw in flex hose connected to a compression test gauge or don't bother!
With the head on the engine all you need to do is use compressed air to stop the valve dropping. Smash the porcelain off an old spark plug and solder on an air hose fitting. Use high pressure and it will be fine. Even with some piston ring blowby there is enough pressure.
Posted 2008-07-05 01:58:47
The method i described is the SIMPLE method, yes, if you want more cost buy a compression tester, it will only tell you what you thought anyway, i have a low compression!!
By your method of using compressed air to remove springs, what happens when the collet ring is tight? you need a socket and hammer to free it, and if the valve opens without freeing the colletts, you release the air from the cylinder, perhaps resulting in a face full of petrol if working on an inlet valve?
I have used the method of brazing in a schaerder valve into a spark plug, and by putting the piston on TDC with the valves closed,apyling air, then listen at the carb,exhaust, engine breather, i can then determine where the compression leak is and what kind of overhaul the engine needs.
Posted 2008-07-05 13:21:22
My plan was to remove the spark plug and put the piston in the top position with the valves closed, then feed a soft nylon rope in to the cylinder before removing the spring.
I told my plan to the mechanics, where i did the job, but he said that just putting the piston in the top position with the valves closed would be enough, because the piston would stop the valves to fall into the cylinder anyway, he said.
Posted 2008-07-06 18:28:38
Hi Lickey, A Schrader valve is really great for a cylinder leak down test but I prefer the security of a click on air line fitting. I have 5 I made up, which covered most cars back in the day.
Hans, if you got flat top pistons or semi-flat tops it's a waste of time! Even with crowned pistons I can't see how it will do anything. With the piston at TBC & the valves closed if a valve drops it can only move 1mm maybe 2mm and it's bottom edge will rest on the piston. Having compressed air in the cylinder allows you to break the tension in the assembly when you push on the tool handle and 110 psi will hold the valve!
A tight collet? Socket and hammer? Your pulling my leg! First use a valve spring compressor. Then ease em out of their seat with a small flat screwdriver. Unless your got some obscure make and model that has an unusual type of collet or deformed collets because they where made with inferior material I have never seen collets that need to be hammered. You don't want to end up with a bent valve!
Do you mean to tell me you haven't isolated the EFI by removing the fuse or relay? Even with a carby motor your not going to get a face full of petrol. Disconnect the battery too. Got your safety glasses on? Protect your eyes at all times.
Ok, you don't want to spend 1500baht on a real compression tester. Well at least get a push in gauge with a dial indicator. But you need someone to turn over the engine with that type....unless you got long arms or a remote starter. It's really important that the each cylinder is within 10% of the average of all the cylinders. If you got one bad one your performance/ fuel economy will suffer.
Think of an engine as a mechanical sympthony and the cylinders as musical instruments. If one instrument is playing off tune the whole sympthony sounds crap! Wouldn't you agree?
Edited by BSJ, 2008-07-06 18:42:47.
Posted 2008-07-06 18:43:56
OK, I'll bite. What's the big deal about not removing the head. You'll spend more time fiddling around finding top dead center on every cylinder and then struggling to compress the springs and remover the keepers.
Removing the head will allow you to have a look at the cylinder walls and also inspect the ridge at the top of the cylinder. If you can catch a fingernail on the ridge, you can plan on a major overhaul.
Posted 2008-07-07 01:46:09
Bsj, hi, youve never come across a tight collet/spring retainer ring? Ive used the best Sykes Picavant spring compressors avaiable, and even with the head off, these will not shift a tight collet ring, so a quick impact is useual in these cases, hence the cord in the bore to cushion the impact on the piston and valve, im not disputing your method or anybody elses, Ive had 40 years in the trade and had enough of todays motors, lift the bonnet and all you see is plastic and wires, give me a big diesel gen set anyday!!
Best regards, Lickey.
Posted 2008-07-07 02:10:35
In many ways you are right, as long as the misfire has been eliminated by changing the plug and HT lead and Dist cap if cracked,
A compression check is fine, but tells you what you already know, doing a leak test on the all cylinders will tell you a lot more, ie, valves or piston/rings, or even a tight tappet clearance, TDC needed for this, quite easy to do.
Taking the head of is gettiny pricey nowadays, with OHC engines, head gasket sets, replacing the "stretch" bolts ect, but on the other hand, replacing valve stems seals is only delaying the inevitable, the valve stems are worn or the guides are, and if they are worn, whats the rest of the engine like? Time for a major overhaul methinks..
Posted 2008-07-07 10:33:32
Good! Lifting the cylinder head might be the best solution elsewhere, but here in Thailand i always feel a great deal of hesitation because of the lack of competence among the mechanics.
My cylinder head has been off three times since the beginning of this year. The first time was a real mess, so i changed to another mechanic. He got it almost right, but only with a small oil leak at the cylinder head. The leak was only to the outside, so i decided to live with it. A few weeks later an oil ring broke down, and i thought of living with that as well, but the oil consumption just got ridiculously high.
I then gave the same mechanic a second chance, and apart form that he was stupid enough not to change the valve seals, his work has been very good indeed.
So, the number one very reason not to take the cylinder head off was that it might not be as well done as the previous time. Quite likely, it wouldn't be, i think.
The second reason was to save money. I saved about 5000 THB this way.
Posted 2008-07-07 11:20:58
Hans, are you sure you are in Thailand? A friend of mine had a timing belt break. It ended up breaking the cam, cam bearings and bending valves. I advised him to find another engine but he had it repaired. The entire bill, parts and all was about 8,000 baht. That was a Mitsubishi turbo diesel.
Posted 2008-07-07 11:45:26
Yes, I'm sure, and i went to a cheap place where they used cheap replacement parts when it all started. That's the place where it became a mess!
Possibly there is somewhere a good mechanic using cheap replacement parts, and the result would appear just as good provided that they were lucky about the quality of the cheap replacement parts.
I'd be very interested, indeed, to have the contact details for the place where your friend went! It'd be very interesting have a look at the place if i'd get nearby!
Posted 2008-07-07 12:47:43
I can recommend two shops in Nong Hin, Loei province. Neither look like much but one in particular does very good work and he guarantees his work. If you saved 5,000 baht in labor, you got ripped off big time. Labor is cheap. Most parts are also cheap but even cheap parts cost much more than labor.
Posted 2008-07-07 13:41:55
Labor _and_ the new additional parts were included in my estimated price, but i actually only had to pay 800 THB to have the seals changed since i replaced them from the top. That price, he said, was only for the parts them self. I think he didn't want to charge for the work since i had to do this because he decided not to replace the seals in the first place.
I'd be interested to get the contact details of the two places you could recommend!
Posted 2008-07-07 14:58:42
The contact is to take your problem in for them to take a look at. These are small shops.
Posted 2008-07-07 15:25:58
I was thinking that, at the very least, they would have a phone number and an address. That kind of information would be very useful if this problem comes back again, or if i get another serious problem.
Posted 2008-07-30 12:23:23
Does anyone have a picture of what this bottle looks like when attached to the engine?
Or if not, does anyone have a picture of what this "extra-lubrication" system looks like when attached to an LPG powered engine?
I'm looking to buy a used LPG powered car, and I wana know what this extra-lubrication looks like. Thanks.
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