I had a similar problem with my 603 motor. The system held a LOT of pressure, sometimes for days. Turns out I had a cracked head. By the time the new head, gasket, valve job, etc were installed, I was looking at a $5k repair bill.

I hope you are not in the same boat, but if you are, just remember once it's fixed, it should stay fixed for a LONG time.

Best of luck!

__________________
Lance Allison
Lance@LanceAllison.com

Current:
11 MB S550 4Matic, 55k miles, Designo Black/Black
14 Ford F150 XLT Lariat Crew, 73k miles, 5.0
Coyote V8 4x4. Black/tan.
09 GMC Envoy Denali, 5.3 V8, 4x4 SWB. 38k miles,
Jewel Red/Med Gray.

Gone:
87 MB 300SDL, 320k miles, Astral Silver/Blue.
98 VW Jetta TDI, 488k miles, Classic Green/Gray.
85 Olds 98 Brougham FWD, 4.3 DIESEL V6, 80k
miles, 3x Gray.

MBCA Member, Chicago Region

I've replaced the water/ethelene glycol antifreese mix to Evans waterless antifreeze in my '87300SDL. I costs about $25 a gallon but I think it is worth it. Since it doesn't boil until 375F, yes three seven five, there is no pressure needed in the system to keep it from boiling. To keep the pressure to zero, just leave the cap loose.

This makes water pumps, hoses, radiatores, heater cores ETC. last much longer because the are not operating under pressure and the waterless anti freeze is not corrosive to anything like a water/antifreeze mix always is. It eliminates the need for frequent anti freeze changes so in the long run may cost less.

P E H

wow PE - do you really leave the cap loose?

__________________
Jim

How would a vehicle owner Prevent a crack from happening?

Usually......it indicates that the engine has been run hot. This may have occured MANY miles ago and the fatigue has just now took its toll. Loose head bolts can create the same problem, and a leaking injector can shock the head, especially in a diesel.

Then there is always the "it just plain got tired".

New heads are expensive, but far cheaper than another car and will last a LONG time.

Note here, NEW head, if it is temperature or age fatigue, a repaired head will last less than one year. The repair may be great, but the rest of the head is fixing to go.

Good Luck.

(Been there done this have the tee shirts.....)

Oil dribble into the coolant in a bad head gasket most of the time. I'm watching mine (on a trip to Florida this week) to see if it is still collecting or just left over from when the rad blew (new rad when I got the car).

If Block Sealant fixed the oil leak, the gasket sealed enough to prevent the oil leak, but is now to the stage you need a new gasket.

I've heard the Elring gasket is a problem, use the other suppiers (name forgotten at the moment!)

The original head was a problem -- warped even in normal use, and cracked when overheated, sometimes without overheating. Replacement is MUCH better -- all rebuilt motors come with new head.

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!

In a truely 'closed' system, if you have zero pressure at certain temperature and you vary the temperature, you will get expansion and contraction and whenever the system returns to that zero pressure temperature, the pressure will ALWAYS be zero. If in real life it does not adhere to these thermodynamic laws, then you don't have a closed system. There is a leak somewhere.

I am suprised to hear of so many others out there who also have this as normal operation. I'd be curious to hear what the cooling system engineers at work would have to say about this.

Tell me more about this Evans waterless system.

__________________
Michael LaFleur

'05 E320 CDI - 86,000 miles
'86 300SDL - 360,000 miles
'85 300SD - 150,000 miles (sold)
'89 190D - 120,000 miles (sold)
'85 300SD - 317,000 miles (sold)
'98 ML320 - 270,000 miles (sold)
'75 300D - 170,000 miles (sold)
'83 Harley Davidson FLTC (Broken again) :-(
'61 Plymouth Valiant - 60k mikes
2004 Papillon (Oliver)
2005 Tzitzu (Griffon)
2009 Welsh Corgi (Buba)

If you have a leak at the water pump, fix that before assuming a head gasket problem. My guess is still a head gasket, but I'd replace the water pump first. Big pain, ain't real cheap, but beats doing the head!

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!

I found out about Evans on this site. Goto: Evanscooling.com.

P E H

A no pressure system may solve a leaking water pump problem and that in itself would pay for the cost of the Evans waterless anti freeze. I plan to eventually convert all my engines to the Evans system.

P E H

HI. Is it possible the old radiator cap was not sealing correctly until the first time you experienced the condition which meant that the system was not working correctly until it started holding pressure?...Given the responses posted to your inquirery it's just a thought.


Brian

This thread made me curious. Just went outside to check my 87 300D. The car runs great in all respects. After 4 hours of cooldown there is zero pressure in cooling system. I suspect, as others have said, that this is the norm.

Dave M.,

Thanks for pointing me to this thread. Some how I missed it in my search for coolant leaks. As you say, the verdict is still out.

If I understand the theory of the cracked head keeping the system pressurized, the cylinder with the crack would need to be compressed at shutdown to force gas into the cooling system and keep it pressurized above the cold state that it started on.

You also mentioned that building pressure fast is suspicious. How long should it take to fully pressurize the system?

__________________
-Mike
'87 300TD 304kmi (RIP)
'95 Toyota Camry Wagon 125kmi

Nope, a cracked head will allow the 1500 psi combustion gasses to leak out into the cooling system any time the engine is running. Usually not enough pressure to force the coolant back in (a good thing, as the rods will all be bent if you try to start an engine with water in it!)

Evey compression/firing stroke will drive gas into the cooling system, the amount depending on the size of the crack or leak in the head gasket. Some cracks work the other way, slowly sucking coolant into the combustion chambers -- coolant dissapears without a detectable leak.

The cooling system should be almost completely de-pressurized until it get to operating temperature, and even then won't get to full pressure unless you have a large heat load, as in driving in traffic with the AC on. If you get substantial pressure below operating temp of within a few minutes this time of year, you have a combustion leak into the cooling system.

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!

Has anyone used the Evans Waterless Cooling System in their Diesel or Turbodiesel? If so, I would sure like to hear about it - cost, benifits, ease of installation, etc.