Re-Torque the Head

[Mark in KS]

The Benz Dr. was kind enough to rebuild my 230SL head last year and I assembled everything back together as prescribed in the torque requirements section.  Now that a year has passed, would it be wise to re-torque the head for safety's sake?

The reason I bring this up is that the temperature guage read higher than it ever has (the 4th dot), and I'm a little concerned that the head gasket may be challanged with the hot weather, etc.

What do you all think?  I did note that the coolant was a little low in the fill tank, too.  Engine performance has been great.  Hans at H&R did a FI rebuild and the engine runs real smoothe.  However, here in KS, the weather has been high temps and high humidity.  Not a good combination for effective heat transfer through the radiator.  Yes, everything is clean in the cooling system and the high temperature guage situation only reveals itself at 4500 rpm on the interstate (at about 75+ mph)sustained speed.

If retorque is recommended, what should be the procedure?  Thanks to all.

I see John in NC is selling his 230 on eBay.  Tell all interested parties that it is a car that could be a real bargain for what he's done to it.

[Raymond]

You have to expect these old cars to run warmer in warm temperatures and slower driving speeds.  There are many posts on the site about larger capacity radiators, fans, etc.  (Don't even get TR started on this)  But you are wise to keep an eye on the gauge.  Sometimes, it is smart to take it easy.  

I have heard from my old retired Mercedes specialist that it is good to re-torque after the engine has been heated the first few times.  You would re-torque in the same sequence as you torque; from the center out.  Follow the pattern in the manual.  

Water cools better than anti-freeze.  For the summer, you may want to consider draining the coolant and replacing with water and a bottle of "Water Wetter".  Just be SURE to put the anti-freeze back in when the leaves start to change.

Ray
'68 280SL 4-spd Coupe

[113gray]

Regarding re-torquing head bolts, some think this should be done on a regular basis, say every year or two. Johio recommends this be done on a hot engine & the coolant pressure be relieved by removing the radiator cap. Each head bolt should be loosened a bit before setting the final torque. The correct sequence is givern in the BBB & the correct torque values also (65 ft/lbs from memory??) Good luck,   -JP-

[ja17]

Hello,
Correct on the re-torque procedure JP (113gray). A 280SL engine uses quite a bit more torque (80 lbs).

Every 12,000 miles is the torque intervals with valve adjustment. During repairs with new head gasket, torque head during installation  then re-torque after first warm up then again at around 500 miles then at 12,000 mile intervals with valve adjustment.

Raymond, correct on the physics of water and coolant. However water will corrode your engine and literally eat a hole in your cylinder head. Antifreeze has anti-corrosive additives to prevent this. Renewing anti-freeze every two or three years is best. mercedes brand anti-freeze is designed for these engines and their specific alloys. Other brands will be ok but more frequent change intervals may be needed.  A 50/50 mix is usually prescribed. As mentioned, too much antifreeze cools less! Too little may allow corrosion.

I have also heard of good results from the addition of "water wetter" with antifreeze.

Joe Alexander
Blacklick, Ohio

[Mark in KS]

Thank you gentlmen.  Sounds like a little valve adjustment and re-torque is just what the doctor orders.  Speaking of "doctor", Dan, why haven't you chimed in?

[Naj ✝︎]

Mark,

 

quote:Sounds like a little valve adjustment and re-torque is just what the doctor orders.

I suggest retorque with warm engine first, then reset valve clearances with engine cold.

naj

65 230SL
68 280SL

[Benz Dr.]

Many new gaskets require nothing more than the initial installation. I do a re torque as part of an engine rebuild if the car is at my place long enough for me to do this. Everything else in these posts I agrre with.
 25% antifreeze with water wetter will give you max cooling I'd think. Pushing the engine in really hot weather to the point of overheating will likely result in damage - some of it unseen that shows up later.
The addition of the water/oil cooler on my car leveled out the coolant temps and gave me about 5 more lbs of oil pressure at hot idle before I rebuilt the engine. On the rebuilt engine, temp never moves and oil pressure stays full - something that's very important in terms of cooling.

Dan Caron's
 SL Barn
benzbarn@ebtech.net
 slbarn.mbz.org

[Mark in KS]

As this topic progressed about engine temperature and heat transfer efficiency, I decided to drain the majority of my anti-freeze mix (50/50) and replace it with a bottle of Water wetter and distilled water.  I probably left about 5+% antifreeze in the mix.

Wow, what a difference.  Engine temperature probably dropped 15-20 degrees with the change of mix.  I studied the "Water Wetter" website and it pretty much anaylzes the best case and worst case scenarios for heat transfer efficiency.  I went from a worst case efficiency (50/50 anti-freeze and water) to a best case (little or no anti-freeze and a bottle of Water Wetter).

Since it isn't going to snow anytime soon in KS, I'll enjoy the high revs and better cooling efficiency of my new mix for a few months.  Thanks for the tips guys, I was really getting concerned about the rising temperatures and the potential for "bad things" to happen.

[erickmarciano]

as I understand . even with an original head gasket I should retorque the head?I have the car for 3 year and never did it

1971 280sl
1962 VW
1954 Allstate vespa
1958 gs150 vespa
1962 gs160 vespa

[Raymond]

I should have mentioned that I use distilled water in the radiator.  I live in Florida where the tap water is loaded with minerals.  It has a heavy concentration of limestone.  So, since I was a kid, all my cars have gotten distilled water in their radiators and batteries.  I forgot that there are folks who could actually use tap water.  Our "hard" water is too likely to cause deposit build-up and "Softend" water has too high a salt content.  

I haven't run water only in the Pagoda, but the only overheating problem I ever had was when the head gastet blew shortly after I bought it.

Ray
'68 280SL 4-spd Coupe