I'm not clear on what you mean about the green coolant, or just making a point, however, Green coolant vs. mercedes pink, has only to do with different levels of Ph. The pink is not as acidic as the green and will minimize corrosion pitting that occurs around the head gasket coolant ports, and does not inhibit cooling as far as I'm aware!

I think TOKNOW, (my other email address is "SPARKADUBIE") ha ha, he he, anyway, I think the point is well made with respect to the PC's. My only question with this is do you think higher heat is generated as a result, or no change in heat, but heat concentrated in one area?

Remember nearly all heat generated from the engine is performed between cylinder and head with coolant passing around cylinder sleeves and passage through the head. A lot of the heat within the cylinder is pushed out the exhaust valve. It is my belief now that between the original trap oxidizer, heat generated from higher and more extreme combustion ignition from the turbo and alda fuel enrichments, inclusions and poor castings, and very likely too TOKNOW's observation, all contribute to weaken bond of the molocules in the aluminum head and the area around the exhaust valves and then one day a hose bursts, or the old radiator can no longer keep up with hot summer's day, or the clutch fan has gotten greatly weaker and doesn't turn as fast anymore, or maybe the thermostat, or water pump! It overheats and cracks period...

This is all interesting but I am still not sold. Mercedes redesigned the heads a few times on these so maybe even the Mercedes engineers were at a loss. Or their are a few things that combine to cause a good head go bad. Maybe the comdination of coolent, driving style, and overheating all cause these heads to crack. I don't think mileage on the head has much to do with it, however the more the better.

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2016 Corvette Stingray 2LT
1969 280SE
2023 Ram 1500
2007 Tiara 3200

Hattie, it's not a question of "good head" or "bad head". A "good head" cannot go "bad". If the casting has flaws internal to itself, these flaws, will, over time, generate small areas where localized cracking of the aluminum will occur. If the area is in a critical part of the head, then the life of the head is limited. Now we can discuss all the limiting factors until we are blue in the face. The variables are many and the strength of each variable is different for each specific vehicle. Overheating, maximum power operation, EGR use, trap-ox, engine cycles, are all variables. Nobody really knows the strength of each variable and whether one or more than one variable will effect the failure. However, I can tell you that no one variable can cause the head to crack unless it is predisposed to crack due to a casting flaw.

If the head is strengthened, it is less likely that any localized cracking will propogate and cause failure of the head. But, how much to strengthen it, and where to strengthen it, is a bit of black art.

Cracks in the head may cause overheating? Hmmmm, well anything I guess is possible, but I wonder how that would play out?

Just a thought, and I can never know for sure, but the previous owner had removed the insulation glued to the underside of the hood, plus removed the underbody panels, the radiator was fairly new, I wonder if there had been a persistant cooling problem occuring sometime before they abandoned the car having checked all possible reasons for overheat but could find none, thus removing insulation, panels etc.?

Steve, I think that you may be looking in the wrong place. The ALDA will add additional fuel during part throttle conditions. It will richen the mixture somewhat and thereby provide more power under conditions less than full boost.

Once the turbo achieves full boost, the ALDA is effectively at its limit and the full load screw determines how much fuel it gets.

You probably will not make noticeable differences in 0-60 times with the ALDA. You might, however, kill your fuel economy by creating an overfueled conditon at part throttle.

Mercedes coolant (aka Xerex G-05) has different corrosion inhibitors. "Green" coolant (the dye is to indicate anticorrosion package, by the way) will damage your hoses AND allow terrible corrosion of the aluminum parts, along with considerable scaling that is difficult to impossible to remove.

Leading cause of radiator failure on these cars is using green coolant and failing to change it often enough. Rad gets clogged with phosphate salts of aluminum, hole grow around the cooling passages in the head, etc. This happened to my sister's Volvo 740 Turbo -- I'm not sure if the head gasket blew first or the rad went, but there was only a small area at the head gasket ring on the head that was NOT corroded away at the coolant passages, so I think the head gasket went. Had to get a new head. Not cheap.

You are about the right age for the hood pad to fall apart -- hopefully no one "fixed" the old one or installed a new on with liquid nails or something, getting all that crap off from a bad glueing job is a PITA -- I spent at least a couple hours getting my hood clean a couple weeks ago. New pad isn't bad if you don't have a mess up there -- scrape all the residue off after covering the engine with some disposable plastic, spray down with carb cleaner and wipe as much of the adhesive off as you can (factory stuff and 3M will come right off), then fit pad dry. Stick a broom behind the hood latch to hold the pad up, peel the top back and use 3M Super Weatherstrip Adhesive, #8090 (there are others, use ONLY the 8090!) to glue up -- two or three very thin coats on pad and hood. Allow to dry 10 minutes or so until just barely tacky, then roll the pad back up and press firmly. Will stick permanently at once! Peel the bottom up, use the broom to hold it, and repeat the glueing for the bottom.

I highly recommend finding some sound encapsulation panels. You can run with the front only, but must hav ethe front panel to install the rear one -- if the front is missing, the rear one bends down and hits the road.... running without them may in fact reduce cooling, there is a slot to draw air down off the rad!

If you are running hot and using coolant with no leaks, it's head time. If you run too warm in traffic, but cools down nicely in open road conditions, the visco clutch is shot.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Ya, I'm getting that feeling too! The vac/pressure guage I have is a cheapie and only reads pressure to 10 psi, I've pegged the needle to the needle stop that is located about what would be 1 pound beyond 10, so I'm guessing beyond 10 and also the guage may not be very accurate at all and maybe I am realizing 12 psi ! Who knows?

I need to get a that guage everyone here talks about, cant think of the name of it off hand, then I can know for sure.

PsFred, thanks for that tip about the hood insulation. It is something I want to do soon. I have thought about adhesives too! But realizing how even the factory glue failed, or if the insulation failed to hold onto the glue, either way, I thought I could resolve this issue once and for all by incorporating either wood, or metal, battens running side to side forming and arc mechanically holding the insulation in place. Also, I wonder if it would be beneficial to buy a product called "Sound Down" it was developed to insulate gen-sets from sound and is of some type of highly dense poly-foam and optionally comes with a lead lining too!

Steve...........

The adhesive doesn't fail, the foam disintegrates into a gritty nasty mess. The new pads are a compostion material, fabric-like face with a nice aluminum insulator over the exhaust area, foam backing. Very nice. About $65, the adhesive will run you about $15 and you will only use about half the can.

Just make sure you have any loose material and as much adhesive off as you can, else the new adhesive will be sticking to dirt and dead glue.....

Cracked heads cause overheating because you are blowing combustion gases (very hot) into the coolant. The heat is a problem, so are the gas bubbles as they reduce cooland density and hence capacity.

Lightenings are nice boats, I wish I lived close enough to a decent sized body of water. Sailed FJ's in the collegiate sailing club for seven years.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

You didn't say Peter where you get the underhood insulation, and assuming it is pre-cut, do you get it aftermarket, or from MB?

Also, I have no underbody panels. They were removed from the previous owner and are long gone! I'll have to find some.

Yes, it was the only way I could understand the increase of heat too as a result from cracks within, and this type of situation should easily make it's presence known by adding pressure into the cooling system. And as most of us know, the cold start-up and squeeze the hose trick for instant pressure should result. Hope I never have the problem!

I haven't yet sailed my Lightning, it is spelled that way! I recently sold my Alden 33' sloop as slip fees and insurance were cutting into my budget so I desided to buy a trailerable sailboat but that would be no slouch as a result. I looked at Rhodes 19's but a friend had this one for sale. I just didn't have time this year, as I have been very busy as you can tell with my "hobbie" as I like to think it as, this 300D! Hopefully next summer I'll have the time!

Steve........

Yeah, a 33' boat will eat money! My sister's father in law is facing having to sell his so he can afford a place to live -- dues are $400 a month to anchor out in the harbor, no slip! I shudder to think what slip fees would be at Coconut Grove!

The hood pad is available precut (with nice aluminum heat sheild attached) here on FastLane, about $65 I think. Fits a bit better than the factory one, being a little bit longer and wider so the ends are under the frame all round, this helps prevent sag.

The factory adhesive works very nicely and is almost always still there, but the foam comes apart and falls off, leaving only the glue.

The new pads are pretty nice, but you could use anything light enough to stay up under it's own weight. Unless you put something very heavy in there, it will stay up until the foam fails, in which case you want to replace it anyway or it will fall out in bits. My old one, a replacement, started to peel off in the back and over the exhaust manifold because the foam disintegrated at the metal side, nothing was gonna hold it up.

I'd scope out junkyards for the underbody panels, they are a bit pricey new. As a said, you can run with only the front one. Unique to the diesel, sadly, although I think the gasser one will fit. it will have a large hole to accomodage the oil pan of the M103, but better than than none -- they do keep water off the alternator!

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

The old prechambers were vertical, the newer (~1990-up) are inclined/angled. The purpose was mostly for emissions reduction, though. And once the crack gets bad enough to where you get the "high cold pressure" symptom - which is usually the first & earliest symptom - you WILL see higher operating temps than normal. Trust me, I've seen this myself on my car, and also a co-worker's. It's not so much an overheating thing, but you can see rapid (and large) temperature swings that would othewise not occur with a good head. And under heavy load you can get overheating, particularly in high ambient temps.

Dave, when you say higher temp readings, what is the guage indicating, as if running while more stabilized, such as driving at a constant hi-way speed?

My temp guage will rise from just over 80c to 90c and back after a hill climb, or putting my foot into it for a short blast.

What I would see is an odd jump from the usual 85-90C, to 95-100C, with little or no load. Or short bursts of heavy load would push it over 100C, which it really shouldn't. With a good head & cooling system, that would not happen. I forget details now, I haven't driven that car in over a year, since it was wrecked (rear-ended by an inattentive driver). My car with the good head has much more stable temps.

It is perfectly normal to climb from 80-85C, up to 90-95C, with a heavy load though - like climbing a hill, or using WOT for a short blast (10-30 seconds). Extended heavy load (especially in high ambients) can jump things to 100-105C but it usually will stabilize there, if the cooling system is working properly, and the head isn't cracked.