1970 280 SE M130 leaking head gasket
 

I just confirmed that I have exhaust gases in my coolant and I have observed disappearing coolant.
Because the head gasket was replaced just several years ago with less than 10,000 miles on the engine since I have to assume that either it was a bad or the wrong gasket, it was installed improperly or I have a warped head and or block deck.
Does anyone have any leads on M130.980 head gaskets for a 1970 280 SE?
Brad

https://hmcmercedes.com/product/mercedes-m130-head-gasket-1300162720-genuine-nos-nla/

or get the entire gasket set

https://www.***************/catalog/c/mercedes/1970/1193341-280se/20-engine_parts_seals_gaskets/5416-cylinder_head_gasket_set?s=d&page=1

When you get the head checked make sure the top and bottom are parallel.

There is a lot of crucial info on rebuilding these engines on the sl113.org site, but you will have to join to get it. Entirely worth the price though.

bc:
It may be worthwhile to take a shot at re-torquing the head bolts; there is no downside.
Remove the bolts one at a time, clean the threads, and relube the threads and especially under the bolt heads. Re-torque to the first two of the three tightening steps. When all have been tightened to step two, then go thru the pattern at the third step.

Should I use the pattern for the removal, cleaning and replacement?

Thanks for the advise.
By parallel you mean straight I assume. And yes if block is straight then good I can get head machined if needed without removing whole engine.
I have been a full member of sl113.org for many years and indeed it's worth every penny.

Brad

That will not be necessary for the one-by-one, only for the final overall tightening.

"Should I use the pattern for the removal, cleaning and replacement?" Not necessary but it sure wouldn't hurt. I'd just break them all loose before completely removing every one.

First things to be done should be a pressure test, check for straightness and minimum head thickness. A problem with any of these could be a deal breaker for that head. Tell the machinist why the head was removed.

Next would be a vacuum test on each valve unless you plan on doing a valve job anyway. Replace the valve seals while the head is off.

Check the block for straightness.

Good luck!!!

By "parallel," rumb means, is the height of the head, the same in front, as at the rear, or has it been machined poorly during previous head work...in other words, the top surface of the head, where the valve cover sits, is not parallel to the underside of the head.

The correct way to check how well the valves seal against their seats is to poor lacquer thinner into the ports, and see if it leaks passed the valve heads. If it does, the seats are leaking combustion. How much/fast it leaks, indicates how bad the leak is. A minor weep of the thinner can either be ignored, or typically cured by just hand lapping. Anything more than that would need the seats and back sides of the valves touched up by actual head machining tools (seat grinder and valve surfacer). Check the valve stem play in the guides, and check the guides for being loose, or for being cracked at the surface of the head. If you have excessive play between the stems and guides, new valve stem seals will not keep the engine from consuming oil, and smoking.

Tolerance for warp is only about .002" for both the head and block. Also, the head should be machined mirror smooth, so if a machine shop cuts too fast or too aggressive, and leaves lines or gouges, the headgasket will never seal, or hold a seal for very long.

If you're going to attempt a retorque, drain the coolant to a level below the head, so that you don't have coolant getting in between the loosened head bolts and the block. I've never heard of removing head bolts during a retorque. Simply giving them a 1/4 turn or so looser, and immediately bringing them back to torque spec, has always been fine. Typically this doesn't work because the fire rings have already been cooked, so re-crushing them just cracks them, and they continue to allow combustion gases to be forced passed, and coolant to be sucked in.

Sorry you have to go through this. Been there a few times, with many vehicles that had aluminum heads.

I am out of my depth with this job so I have some basic questions before I try to do this.

First do the bolts ever need to be replaced?
Second is the procedure always done with the engine cold?
Third can you push the torque spec any?
Thanks
Brad

"By "parallel," rumb means, is the height of the head, the same in front, as at the rear"


not just F to R, but also "thickness" side to side.

There is a minimum thickness spec for these. Shim are available for the cam towers if the head get shorter. If you have to shave the top of the head the cam gets closer to the valves and has to be corrected.

Loosen the head bolts that hold the cam down first and evenly, then you can just do all the rest.

If your head ends up unusable I think I have a local source on a 280 head.


As mentioned do a wet/dry compression test first to see if the rings are still good. Either way when you take the head off you can measure the bores.


My personal experience is that the M130 line of engines only really last 100K miles and then everything is worn out on them (except the bearing shell -they always seem to be in excellent shape.)

1) If the condition of the bolts, and in particular the threads, is such that corrosion over a long period of time has removed noticeable amounts of metal, then yes, there is cause for replacement.
2) Engine cold, yes.
3) By removing, cleaning, and in particular lubricating the threads & undersurface of the bolt heads, the applied torque of the wrench will most closely result in developing the intended tension in the bolt, and as a consequence, the necessary clamping force.

Another tip I forgot to mention: Purchase a new Snap-on allen socket, and prior to loosening any head bolt, use compressed air and an air gun to blow all the oil and crud out of each head bolt socket. Place a rag over the head bolt before you hit it with compressed air, so as not to blast yourself in the face (and the engine compartment) with a bunch of goopy oil and sediment. If you don't do these 2 steps, you are extremely likely to strip out the allen socket in the head bolt. Once you do that, your are extremely screwed.

Ok, ya'll are going to love this. I have a friend who rebuilt two Stanley Steamers and several various 1920s Rolls Royces and Bentlys. He heard about my problem and has offered to help. He NEVER touches anything that is younger that 75 years old.
Turns out his parents bought new a 1970 280 SE Sedan and helped them with it through almost 20 years and 260 thousand miles of use.
Brad

Thanks Todd.
I was a kid in the late 60's and watched just what you described happen several times. I really think maybe I will invest in a proper gasket replace with an evaluation of the head and valve seats. Valve guides are probably fine given the lack of oil smoke but lapping the seats may be a good idea. Anyway I have to check the head and block and hope the block is straight at least.
Brad