w126 500se smoking

[FizzyFarmer]

Hi i have a w126 500se that i have only owned for a couple of months and it has just started to smoke a little when idling. It has been driving beautifully and there was always a little occasional puff of smoke when idling but it seems to be getting worse. Is this due to the engine running too rich or is it a valve problem. How can i tell?

 

[television]

If it smokes after standing at the lights,for instance when you pull away, its valve guides. If it smokes under acceleration its rings.


If you have a compresion tester, take out the plugs, take a reading on the first stroke,squirt some oil in the plug hole, if the compression comes up it the rings/bores, if it stays the same its valve guides.

Malcolm

 

[scotty2hotty81]

valve stem seals "common"

 

[Ian B Walker]

valve stem seals "common"

Agreed good luck

 

[FizzyFarmer]

thanks for that. It smokes when standing at light etc not when under acceleration. I have it booked in next week to be looked at so great to have a bit of knowledge! thank you for the replies. If it is the valve stem seals is that a pricey thing to fix

 

[carabind]

Cheaper than rings and a rebore ! It's labour intensive though and will depend if the heads need to come off (as these are seals, not the actual guides), if not, you might be in luck. Someone will be along soon who will know your engine better than I and can answer better.

 

[Ian B Walker]

There is a way of doing it without lifting the head but it is not for the faint hearted. Remove the plug. Move the piston to its lowest point, Pack the cylinder with cord though the park plug hole. Move the piston upwards and compress the cord. Then use a forked bar under the cam and over the valve spring and lever down. Remove the collets and ease back up. Remove the spring and renew the valve seal. Reverse the procedure, remove the cord and move onto the next one.

 

[carabind]

As Ian says, not for the faint hearted. The compacted cord stops the valve from dropping down into the bore. If this were to happen, you'd have to remove the head to extract it. The greater the number of cylinders, the bigger the risk if you did this at home , I guess. But a good indie would cope

 

[scotty2hotty81]

where i work we have an adapter that screws into the plug hole, and fills the chamber with compressed air, all sorted no chance of the valve falling in!
god i miss proper jobs like these dont see them anymore.

 

[FizzyFarmer]

thanks

I will definately take it to my mechanic who hopefuly will be able to sort it out. Many thanks for all the advice and i will keep my fingers crossed!

 

[television]

I look back and think the same thing, I used to cast my own white metal bearings, line bore, scraping and engineere blue, gapping piston rings, even had ICI coarses on spraying and cant even do that anymore. what a waste of knowedge.

malcolm

 

[Mikesmerc]

Fancy a foxer white metaling the big end of a 1920s single cylinder (about 13litre)Lanz Bulldog Malcolm:-D . Used to be a hand full doing that sort of work over here but are now long gone, what a pity.
Mike

 

[Ian B Walker]

Fancy a foxer white metaling the big end of a 1920s single cylinder (about 13litre)Lanz Bulldog Malcolm:-D . Used to be a hand full doing that sort of work over here but are now long gone, what a pity.
Mike

Tell me about it. i am renovating an 8 cylinder 1947 Buick engine for a collegue. All the bearings are cast into the con rods. Can I find someone to re do them, can I bu**ery

 

[FizzyFarmer]

hi i took the car to the mechanic and his advice was check the plugs in 6 months and then you will know because a compression test wont give you the full answer. Also i contacted the previous owner who said his mechanic had put the smoking down to carbon build up and if you arent doing long runs this can get quite bad in these older big cars because the exhaust system is so long and becomes much more noticable when the weather gets colder! does this make any sense to anyone

thanks

 

[FizzyFarmer]

No more smoking!

well it looks like the previous owners mechanic was right! i have just come back from a long run to dorset and back and the car isnt smoking anymore! My mechanic laughed when i told him if it might be a carbon build up problem he and the the mechanics had a good laugh! hopefully thats the problem solved. amazing and thanks for all the answers and advice

 

[television]

Tell me about it. i am renovating an 8 cylinder 1947 Buick engine for a collegue. All the bearings are cast into the con rods. Can I find someone to re do them, can I bu**ery

I wonder if this could be done by modern metal spraying technique.

Malcolm

 

[Glenn Smith]

hi i took the car to the mechanic and his advice was check the plugs in 6 months and then you will know because a compression test wont give you the full answer. Also i contacted the previous owner who said his mechanic had put the smoking down to carbon build up and if you arent doing long runs this can get quite bad in these older big cars because the exhaust system is so long and becomes much more noticable when the weather gets colder! does this make any sense to anyone

thanks

Yes and no! first thing i do with a smokey engine is check all the breathers are clear. Not sure what checking the plugs after 6 months will do, a good mechanic/technician will be able to accurately diagnose the fault, there are several methods of checking for worn valve guides-seals and rings/bores. If these particular engines are prone to valve stem seals then i'd look very closely at that.

 

[FizzyFarmer]

spoke too soon

aaah maybe spoke too soon. After a couple of days of slow town driving the smoke is back! does this sound like seals. It seems from what everyone is saying then it probably needs to be looked at, but seems strange that with a big blast on the motorway and some hard driving it dissapears. any ideas? My mechanic has been great in the past but just wondering whether he doesnt really understand these big engined older cars, maybe need someone with a bit more w126 knowledge for could go a bit round the houses with him.

 

[scotty2hotty81]

Really need to get those valve stem seals changed mate, find yourself a well established mercedes specialist to do it, give it to someone who has not done them before could mean trouble :sad:

 

[gordonm]

Just in the process of renewing the valve stem seals on my 1980 350 SL using a small compressor and fitting to pressure the cylinder with compressed air.
I agree not for the faint hearted I am managing one cylinder a day, the main problem is teasing the collets out and getting them back in.
I'm hoping it cures the smoky starts I was getting.

1 x VS168 - Sealey Valve Spring Compressor Lever Type OHV/OHC : £14.34
1 x VS1601 - Sealey Compressed Air Adaptor Use with VS160 : £7.81
www.toolstoday.co.uk