Help Identifying my cylinder head

[pauldridge]

I've got my 280 engine apart.  Head is at the machine shop.  The machinist says I definitely need new valve guides.  He's concerned about properly identifying the engine to get the correct guides.  Unfortunately, this engine isn't original to my Pagoda (it's a 230SL w/ 280 engine), and does NOT have a serial number... nothing.. no plate, no stamped number.

Does anyone know if there are differences in any of the 280 heads as far as guides are concerned, or is it a one-size fits all?

Second question:
The engine came out because of extremely low compression.  Turned out, 4 out of 6 pistons had slightly melted along the 2nd ring land (same area on each).  The cylinders themselves were not damaged.

 The pistons in this engine (the damaged ones) are 3 ring pistons.  I have another 280 engine I bought for spares which has serviceable 4-ring pistons.  Is there any reason I couldn't use those 4-ring pistons in place of the original 3-ring?


Finally, were  there different length rods in these engines, or should they all be the same?

[Naj ✝︎]

Hi, Phil

There should be a casting # on the head below plug holes 3 and 4 "130 016 xx 01"

Use the head gasket chart to determine 'early' or 'late' engine.

http://www.sl113.org/forums/uploaded/ja17/200622265426_Cyl%20head%20chart%20Joe%20A%204-04.JPG

You will need to measure the o/d of the guides to determine wheter they are standard or oversize.

Not sure about pistons....

Naj

[ja17]

Hello,

The guides for the M130 (280) engine are the samein any version, early, late, etc. even though there are two distinct cylinder heads for a 280 SE, SL.  In fact even the valve guides for the carbureted 280 engine are the same. In short, all M 130 engines use the same intake valve guides and the same exhaust valve guides.  Different oversizes are available in the event that the holes in the head are two big for a standard guides. Oversize guides are not usually needed unless a valve guide has come loose in the head causing the hole to enlarge.

M130 280 pistons will not work in your 230SL engine. The diameters are way different among other things (possibly different wrist pin diameters) .  

In any case using diffenent styles of pistons in the same engine is asking for problems. The different weight of the pistons could cause some major engine imbalance. Always check the cylinder wear and ring groove wear before using used pistons.  Ring grooves are checked by inserting a feeler gauge in the space between the piston ring and its groove. Mercedes allows about .004"   If the ring groove becomes too wide, the ring can twist and break.  


Using the differnet connecting rods is not possible . Besides a huge weight difference, the oil supply holes in the rods are different. Also  the wrist pin size  and the rod bearings are also different.

[Shvegel]

Joe,
I think he is rebuilding a 280 engine in his 230 chassis and has an unidentified engine(early/late) as well as spare used Pistons and Rods.

I think what he was asking was if 4 ring 280 pistons replaced as a set would be OK in the 280 engine that has 3 ring pistons currently installed(I seem to recall a design change in there somewhere from 4 to 3?). In other words is a 280 piston a 280 piston or is there a difference between early and late?

Also if the early/late 280 rods are compatible?

Pat

[ja17]

Thanks for clarifying that Pat.

Yes, most likely the pistons could be swapped.  Now the rods are anther story.  You will have to compare them. There are  two different  styles.  The rod bearings and the rods must be the same or changed in sets.