Will re-torqueing the head cause more leaks?
 

Thanks for your intrest..
On the 96 E300D there is a definite water leak, not too bad yet, toward the back of the block and head. If I attempt to re-torque the head, am I asking for more leaking by causing the gasket to separate even more?
Matt Hemsley
So.CA

Matt:

If you have a leak between the cylinder head and engine block >> no amount of torqueing is going to "solve" the problem..

It's a major issue for your engine and best "solved" by replacing the head gasget.

To try to run the car with a blown head gasget risks engine overheat which usually results in warped head that necessitates having the head machined back to being perfectly flat... which usually changes the compression .... and usually things "just aren't the same anymore'..

I've done head gasget replacement on my BMW 2002's >> not the most fun job in the world... but doable

good luck

You should never try to re-torque "stretch" type torque to yield bolts!!

Thanks for the replies, I'm not seeing any symptoms of a blown gasket other than the anti-freeze slowly dripping out. The car does not overheat, there's no oil in the water or vice versa. Are there any other places anti-freeze can escape besides from the gasket? It's coming from the area that has a half round bore into the head. I did take it to a indie yesterday who recommended I drive it until it gets really bad(lots of water coming out). Also, I'm not sure I know what "yield bolts" means. One last question, what are the most likely causes for this happening?
Thanks
Matt Hemsley
So.CA

Could be a leaky soft plug! But I am not sure where they all are!

When the bolt is torqued, it elongates and stretches. The torque and resulting stress stretches the metal to the 'yield' point. Once metal is stressed to the yield point, it will not return to the previous stressed length. It will stretch further with less torque and stress, and is thus weaker.

It is a predictable way to apply a known amount of force to hold a head, but it means that the bolt is good for a 'one shot' use.

Best Regards,
Jim

Jim,
I totally understand now about the "yield bolts", thanks for the easy to understand explanation. I am really interested in the "soft plugs" as to whether or not this may be the problem. Anybody familiar with these and where they are?
Thanks,
Matt Hemsely
So.CA

They are the little round plugs that are about 2 inches in diameter. They can be seen all over the engine block.

Soft plugs are used to prevent damage from water freeze inside the engine. The idea is for the plugs to be push out if the water starts to freeze thus preventing a cracked engine block.

Yes and they also can rot out and leak!

I guess I'm used to the old term of "Freeze Plugs" and didn't know if "soft plugs was a synonym. I'll take another look to see if there are any of these plugs in the vicinity.
Thanks everyone for your responses. If and when I get around to replacing the gasket, I'll keep you updated.
Matt Hemsley
So.CA

soft plugs- freeze plugs?
 

If you are losing coolant from one of these babies, its very hard if not impossible to reinstall a OEM plug, without removing the engine block. These plugs have to be hammered in quite hard and straight with a special drift tool, to effect a perfect seal against the block, not to mention the fact that they probably failed due to oxidation (rust) from the block corroding. You also have to wire brush the "freeze plug hole in the block and make it smooth and shinny clean, before you install the new one. They do have various size (emergency) rubber plugs, with an expansion design center bolt that might get you going, but the only proper way to end freeze plugs problems, is to pull the block, and change them all.... Oh BTW....Engine manufacturers use a sand-oil casting plug process to effect all the internal dimensions of an engine block. If you understood the casting process, you would then have to think, hey? How the heck do they remove this huge sand plug mold from inside the casting, after its cooled? Well my dear friends, all those holes that are located by the sides of the block, (freeze plug holes) are really there to allow the sand plug mold to be removed from the block. Bet ya never knew that! Anywho, what do you do with all these holes after the casting process? Ok you got it, seal em up with some flimsy stamped sheet metal plugs, and hope they hold for 25 years..... When some dummy added pure water to his cooling system, because he was a cheap skate and couldnt afford anti-freeze, and the winter came, of course the expanding ice pushed the plugs out, and still cracked his block. So, he then tried to get off the hook for being dopey, and said "gee guys", my "Freeze Plugs" popped out from the ice, and it saved my block from exploding, thank god for those freeze plugs....What a nice dopey guy.....`Enjoy......

Sorry, you are wrong kiddo...read my note

Dave is right on the money. I used to work developing automotive castings, including engine blocks. I suspect somebody came up with the term "freeze plugs" to put a positive spin on something that is prone to problems and doesn't help with the cooling system.

I decided to go ahead and replace the head gasket, thankfully the head was pretty straight and the only thing on the head that needs replacing will be the exhaust valve guides. Whew! One side note having to do with the leaking symptom. On this head there are pressed in ball bearings which are not supposed to come out. The place where the coolant was leaking was close enough to this area that for $40 insurance I'll have the head pressure tested to see if those are o.k. I'll let you know what they find.
Matt

Where are the ball bearings?

freeze plugs
 

well, all that about castings is no doubt true, but they do fail first at least some times. back in the seventies i had a 37 chebby. when i got it it had a freeze plug out in behind the water pump. it was in a difficult to reach place but i was able to put in a rubber freeze plug. these consist of a rubber donut with a bolt thru the center and a large washer on each side. buy one that will fit your hole insert it and turn the nut. it fixed my chebby. i dont see why it wouldnt work on a benz.

as a matter of fact we solved a plumbing problem in my 1913 office building a few days ago using a similar device to plug a 6" d pipe that had been apparently struck by lightning at some point blowing out the back side of it where it was inaccessible and invisible, but allowed noxious sewer gas out.

tom w

the ball bearings are supposedly used to block holes that are used for assembly and there are six sets of them on the exhaust bank slightly above and to the right of the ports.
Matt

I just heard back from the machine shop, and the pressure test was negative, a very good thing. So the ball bearing were not part of the leaking, and everyone I've talked to said they had never heard of them leaking. Bad news is that in the middle of doing the valve seating, he found that the #6 cyl. intake valve was hitting the valve seat ring. Ring up another $48 bucks.
Matt

What does that mean?

I may not be using the right nomenclature, but apparently this is something that does not happen very often. The valve was going past the 45* seat angle which ended up causing the problem.

Doesn't make sense-

Possibly the valve seat is loose.


Michael

.... or valve seat recession.