1991 e300te 4matic I just dropped of the head at a machine shop to get the valve seals installed and get the head resurfaced. To take the head apart and do a valve job it would be over 500 for everything is this a decednt price? It seems pricy to me. How hard is it to replace the valve seals?? Thanks in advance

I just did my valve seals myself for far less cost. Just depends on how much of a do-it-yourselfer you are. I've been turning wrenches since I was 8, and in the last 25 years I've been fixing all my cars.

I have a 91 300E, and since I had to have the head off to replace the head gasket (oil in coolant), I checked the head surface with a machined straight edge and feeler gages. All was well there, or else I would have had the shop resurface the head.

The valve seals require a spring compressor to remove the valve keepers. There is one available at Sears for $20, or a large C clamp and a socket can be used to break the valve stems free from the keepers...but that method won't work putting the valves back together...

The valve seals just pop on and off. I checked the valve guide clearances and lapped the valve seats while I was at it.

Just got back from a 3000 plus mile trip, and the car is running great.

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I did the valve seats myself with a home made tool to get the valve keepers off/on (search on the forum and there are pics). The seals are a piece of cake, the *seats* on the other hand, require some pounding, lapping, and potentially grinding of the valves. Was there a specific problem with low compression caused by a bad valve? also, is the head warped (thus requiring resurfacing)?

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89 300te 222,222
92 300e 190,000

I take it they are going to surface the head and then R&I the valve guide seals without completely disassembling the head???

Once they have the springs off they should be able to "wiggle test" to check guide wear. If they are well worn, I'd suggest you have the head completely rebuilt including new guides. If the guides have over 100K miles, they are probably worn, and if you plan on driving the car at least another 50K miles, it might be a good idea to do a complete head overhaul, which may also require some new valve depending on stem wear. The exhaust valve stems will probably show more wear than the inlet valve stems.

Assuming they have a basic labor price for a head overhaul the add-ons would be for required parts.

Duke

We have a '93 300TE 4Matic. At about 150M miles I noticed an increase in oil consumption. Our indy thought it was valve seals and changed the seals by using air pressure in the cylinder to hold the valve up. He did not remove the head. That solved the oil problem. We have 272M on the car now and it still runs great. We have a small amount of oil leakage through gaskets but I have not changed the valve cover gasket since the valve seal work. The head has never been off.

SRHARVEY
'93 300TE 4Matic, 272M
'83 240D 250M
'82 380 SL 130M

for a '300' head --replacing the valve stem seals is an 'on the car' job about $300 max..

DO NOT RESURFACE THE HEAD. That is a fatal mistake. The 'warpage' spec are generous as the head is quite flexible. I think it allows over 0.030" warpage end to end (and really a lot more--up to 0.060 is OK.) If you 'resurface' the engine side, then when its tightened down, the camshaft side is no longer straight and the cam will ruin the cam tower bearing surface and cam journal, and seize, or break the timing chain,--usually total engine destruction.

To properly resurface that head, the valve guides, cam tower locating pins, and everything else and core plugs on top have to be removed and BOTH sides of the head milled in a planer to ensure the resulting surfaces are exactly parallel. Alternative is a trial and error fitting of shims under each cam tower to restore exactly even height (straight cam). That is a VERY time consuming task, but can be done and will certainly work. The head has to be torqued down (less the cam towers) and then one tower at a time tightened to identify the 'high' one--and by how much. Then shims added under the other towers-one at a time until the cam turns freely in the bearings.

I dont know what you are smocking over there but everything u sayed is rubbish.when u bring the head to a mashine shop and it is warped u can get it mashined.we are mb specialty shop and we have mashined a lot of heads.what kebowers meant was when you do mayor valve jobs and have to grind the seats,than u may have to adjust the valve spring hight to the rockers

I bought a used '92 300e in mint condition but it burned about a quart of oil in 750 miles. I replaced the valve stem seals without removing the head (using air pressure) and the car uses no oil now between changes.

It's amazing how much oil can leak past the old, brittle valve stem seals. If I had a oil consumption problem, I would first replace the seals, leaving the head in place (less than $20 for parts) before going through the trouble and expense of removing the head.

If the head does need to be remove I would have things such as warpage and valve guide wear checked by a competent shop.

Hi all,

what's the minimum air pressure to keep the valves in position when replacing the valve stem seals?

Can same air-in-cylinder to hold a valve up technique work on m119 motor?
thank you

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1999 ML430 Silver 135k ml
Smoked LED taillights, Alpine in-dash DVD player, 12" sub, Pioneer components, 2 amps, 4200k HIDs, ML55 headlights, 20" rims, mirror LED blinkers

SOLD. 1996 E320 145k ml. Burgundy

SOLD but miss it everyday 1992 500sel Black
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SOLD. 1990 300E White
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I'm interested in doing this also. Wouldn't cranking the engine so that the pistons involved in the valves being changed would be at TDC be extra insurance that the valve won't fall in? This is probably the one thing stopping me from doing this - the possibility of disaster in spite of being careful and having the right tools (compressor, magnet, I even bought seal installers).

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86 560SL
With homebrew first gear start!
85 380SL
Daily Driver Project

http://juliepalooza.8m.com/sl/mercedes.htm

This is in reply to using air pressure to hold valves while replacing valve seals. I had this done on our 300TE several years ago. The independent technician who did the work no longer owns his own shop, preferring to work for someone else so I can not get to him with the question. I do not know how much air pressure or any other details only that the job was quite inexpensive and solves the problem I was having of excess oil consumption.

Our '93 300TE has 278M miles onit now and is still a fine running machine. It has 4Matic drive and we have had some minor repairs on that, we had to replace the alternator last winter while in rural New Mexico (we live on the east coast), also I did a R&R with the blower motor. Following the directions from Shop Forum really helped. I have also had to replace the shocks for the tailgate, again with help from Shop Forum.

Sorry I can't help with the question at hand.

'93 300TE 4Matic 278M
'83 240 D 240M
'82 380 SL 170M

I used 50 psi +/- when I did mine. Yes, bringing each piston up to the top of the compression stroke will guard against losing a valve, but I didn't bother.

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1989 300 SEL that mostly works, but needs TLC

I used 100 psi.

Sometimes the valve collet (upper washer) is jammed onto the keepers and you have to give it a sharp rap with punch to release which causes the valve to unseat for a second. With 100 psi, the valve always popped right back up for me.

Having personally done more 103 head jobs than I could ever count I have to say that i have never had a problem with a head that has been machined within the allowable thickness. Never had cam bearing damage, never had to shim cam towers, never had a cam that wouldn't turn freely after the head was torqued. Pulling the guides, planing both sides etc is way overkill for this engine. Sure it would be nice on an ultra high dollar custom race setup but a "fatal mistake" not to....No way.