So, is water supposed to come out of this hole?

[roymil]

...asking for a friend.   

Short story: I pulled out the stud between cylinder #3 exhaust and intake ports and was met with a nice stream of coolant.  I used blue mercedes antifreeze so there is no doubt what that fluid is.  Uhmmmm, why?  Is this normal?  Can I just put the stud back and we'll all just forget we ever saw that?  What could happen?

Long story:  2 weeks ago this engine was purring, idle was perfect 750 RPM, cold start perfect, compression great, leakdown great, power and acceleration great, no smoke, life was good.   I was about to go get it inspected and registered but it had a little grind going into first so I pulled it back into the garage and found the clutch wouldn't disengage and finally killed the engine all together.   After exhausting all ideas I dropped the trany to find the clutch literally glued to the flywheel, not worn out, but stuck so hard I had to pry it off like it was glued on.   It was saturated in thick gooey grease, I dont know why, but that mystery still needs solving.  I have a new clutch ready to install but while the transmission is out I noticed how much room I have in there and decide its a good time to get to that steering idler arm bushing.   Tons of room and the old destroyed bushing comes out easily...and then I notice black soot marks around a couple places around the exhaust.  That's unacceptable, and so with the top nut off of the idler arm I decide the front pipe might just squeeze by the idler mount if I jack the engine up an inch.  It worked!   I got the whole exhaust out in one piece without a lift. I actually used the space where the transmission would have been to rotate the whole assembly and twist it out.   worked pretty nice.   My grandkids helped pull the whole thing out the back.   It's toast, at least 3 leaks, rust, yeah what do I expect after 30years since it was last fixed.  But I'm happy to be getting to these things I had been putting off and rather enjoying being under there.

Eventually  I notice how messy the manifolds are from underneath and they even seem a bit loose.  Sure enough the bolts aren't that tight. OK, fine, its going to be like this is it?   So out come the exhaust and intakes without a hitch.  I got excited investigating getting them cleaned and ceramic coated.  That will look nice!

Then I take a close look at the corrosion on the mounting studs and decide it might be good to replace them, so I pull one out to measure it in order to confirm what I need to buy.   Then I strike @#$%W water!!!  Is this in the manual?   Is it supposed to be an alternative way to drain your coolant?   Am I the first to do this?  About a gallon drained before I got over my shock and took this picture.  Lost another gallon before I thought to just put the stud back and seek professional help. 
Yes, that is YOU!   please advise.

I'm having a nice fine tequila right now just hoping someone can explain why I should just leave that stud in there, top off the coolant, and and not have to pull the head, which will undoubtedly lead to needing to rebuild the engine, redo the interior, and repaint everything, because, thats just the way it's going right now.   Lucky I love to work on it.

Other ideas will be heard, but maybe tomorrow. 

Hope y'all are not having this much fun with your pagodas tonight.

[RAY]

Just read your story which I have no answer to .......... but a great question, never seen that before !

Sit back, have another tequila  and wait for the answers to roll in, i,m sure it won't take long.

[Cees Klumper]

I'll try first: I am definitely not sure, and physically far away from all my spare heads so can't check, but I will speculate that this is not supposed to be like this? I am crossing fingers it's normal, but I am as worried as you are at this point.

[WRe]

Hi,
I know this from an M127 cylinder head in which the stud channels were drilled through to the water channels.
I would take a look into the channel if there are some irregularities.
...WRe

[roymil]

Yes, I was hoping it would be something like that for M130.   I just need confirmation that the #3 cylinder stud is indeed drilled thru to water a channel.   If so, I'd be very happy and then just need to know a proper procedure for replacing it to prevent leaks.   I assume some sort of sealant is needed on the stud threads.   I dont want to guess about that.
any help appreciated. thanks!

[Benz Dr.]

Looks like it's not a blind hole. I use Permatex thread sealer on applications like that.

[ejboyd5]

Did you strike water when removing the other studs?

[roymil]

the only other stud I removed was the one to the right of #1 and no water channel there.   Also, I counted wrong on the one with the water.   It's actually the stud between cyclinder #4 intake and exhaust.    (not #3)

Either way, wondering if anyone knows all of the holes that are drilled through where this could happen, and which are not?

thanks,

[RAY]

Interesting note on your Pagoda's history " Rode in your Pagoda's first mile " .

Did you collect it with your father ?

[roymil]

I did indeed.  It's a distinct memory for me climbing back into that "emergency seat" to ride home.   Also notable because at the time, my dad was mad they had up-charged him for a 280SL when he had specifically custom ordered a 250 and then had to wait extra months for it to arrive.  He lived another 30+years and that was the last car he ever bought. (not counting work trucks)

[Kevkeller]

I’d give Metric Motors a call. I’m sure Mike can answer your question quickly.

[Benz Dr.]

Simple answer is if it is a blind hole, it could be that the stud broke off and someone drilled out the broken piece so they dilled into the water jacket.

[roymil]

Thanks, yes, agree thats possible.  I was also wondering if corrosion in the head during its 18year nap might be a cause, but I wouldn't have thought that could allow so much flow by.   The water pump vanes were very pitted, so it was pretty bad chemistry, and could have etched other aluminum, probably did.

Drill thru sounds more likely, or else its just supposed to be that way.  I have noticed that some pictures of rebuilt engines have the studs in, and wonder if this is part of the reason why.     This was a rebuilt SE M130 that according to the receipt came directly from Mercedes back in Nov '91 but it was installed by a non-mercedes shop.  It does have the legit looking stickers on it, but who knows about quality control back then.  I've already established it likely has the wrong head bolts in it for this version head, (5mm shorter).  Also it has an oil sump pickup nobody seems to recognize, but it works fine.

I'm wondering if there are any drawings of the head that might show the water passages?  They are hidden from sight (top view) but also wondering if one might be able to tell if a new head stud hole was blind or thru hole or not.

[stickandrudderman]

Absolutely no way there should be coolant behind that stud.
You could try putting some chemical metal in the hole and re-inserting the stud; otherwise I'm afraid you'll have to take the head off and either have it repaired or replace it.

[roymil]

Thank you.  Can you confirm thats the case for every one of those studs?  all are blind holes?   Yes, it's looking like pulling the head is the right way to go, especially in light of the other possible corrosion and head bolt issues I've been worried about.   I guess at this point with the manifolds already off it's not that much more work and I'm waiting a few weeks for new stainless exhaust and manifold ceramic coating anyway.

[roymil]

I started reviewing all of the posts I could find about cylinder head removal and found one that confirms that at least one head bolt hole is normally thru to a water chamber.  Be nice to know which.    The other post confirms that water passage corrosion can get pretty serious.   All of which continues to indicate I need to pull the head and assess.

        Pinder :  One thing that messed me up when I re installed the head was that when I re installed the manifold studs I did not use thread sealer. It turned out that one of the studs goes into a water passage so I had a slight leak of coolant coming out. I fixed this by removing it and using thread sealer. it fixed the problem.

           Benz Dr : The water ports in the head will often corrode away and will need to be replaced. Sometimes the head will have corrosion around these water inserts so that would need to be welded.

[roymil]

Here’s an update.   I traded emails with Pinder who remembered his water leak being 3rd bolt from front, or middle of cylinder #3, and I double checked yet again thats where my water spout came from too.   His leak came on a newly rebuilt engine with a re-machined head so I would assume they would have fixed any issue like that if it was wrong.  He said he put some permatex sealant on the bolt, reinstalled it and had no problems after that. 

So that gives some confidence that particular stud hole is supposed to be though to the water passage, but I note not all agree that is correct.

So I thought to get a borescope and I took some pictures.  First one is clearly from a blind stud hole for reference, thats front most #1 stud.  Second is #3 stud hole that leaked, clearly not blind.  Third picture is from nearer to bottom of #3, and the last is looking past the bottom into the head.   It's not the smoothest transition from the bottom of the hole into the head, but it looks like it’s supposed to be that way.  There was no sign of corrosion at any point.   The coolant that drained was a nice & clear mercedes blue.  I feel like a corrosive failure would look much more randomly shaped, with rough texture and discoloring.   I do have some experience looking at SEM shots of all sorts of chemically damaged semiconductors at the submicron level, and physics is physics.  Decay and destruction is typically very random and messy at any scale, whether it’s a transistor or a rusted bolt.

So, at this point I'm leaning back to not to pulling the head.  Mainly because I know compression, leakdown, and power are great.  Never smokes and has very clean oil too.  This is where I was when I pulled threads on that short head bolt a while back.   I figure if I closely monitor the fluid quality and other vitals I should be able to detect a problem soon enough to come back and pull the head later if I need to...and I'll be a lot faster next time.

A wise man once said if it works, don't fix it....but I know there are plenty of wise dudes on this forum too, so I'd be a fool not to listen to any flaws in my reasoning here.
Thanks!

[Pinder]

I had noticed the water coming from one of the threads as noted in this thread several years ago and sealed with permatex. I have not had any leaks since I did this. its possible the machine shop I sent the head did this or maybe its like this in some case.

Regards
 
 Pinder

[BobH]

Someone suggested asking Metric Motors, so this is what Mike replied:

"Yes – we can confirm that the studs for the manifolds do go through to water.
Mostly the center studs in the 230SL, 250SL and 280SL engine types.
  That is partly why Mercedes peens the cylinder head at the base of those studs"

[roymil]

Many thanks!  I had forgotten that suggestion to check with Metric and grateful you did.   This settles my decision not to pull the head, much as I was kind of looking forward to that.  I’ll smear some non hardening permatex on those threads and put the stud back when I get my manifolds back from coating.  Thanks

[Pinder]

I need to give credit to Joe Alexsander who had responded a long time ago and had confirmed that yes as far as he knows some do go into the water chambers.  Its good that metric confirmed this.

Regards

Pinder