Coolant loss.......

[Plantman]

I have had to add about a quart of coolant every 150 miles or so over the past month.

Anyway, I snooped around and found the top radiator hose a bit loose and sign of a small leak.

I figured that was the problem and refilled. I last did this about 200 miles ago and figured I was done.

Today I drove home and the low resovoir light came on again intermittently.

There was a small amount missing yet I could find no leak. There is a small hiss in the area of the turbo but I see no leak.

Question, are there any hoses in the area of the turbo that are not visible from the top?

There is no engine oil in the tank, nor has the car overheated.

I am not very familair with this car yet and can't pinpoint the small hiss/leak.

Thanks

[sixto]

SDL, right?

There are no coolant passages on the passenger side of the engine outside of the block drain and heater hoses.

Sixto
95 S420
87 300SDL

[Plantman]

Yes SDL.

think I will hook up that thing that pressurizes the system and evaluate further. I am positive it is something minor, or it would have leaked a whole lot more.

[psfred]

There is a hose from the coolant tank to the block, and the thermostat/lower rad hose are on the side of the block right beside the turbo. Take the u-shaped air hose off and take a look -- might be a leaking thermostat cover of lower rad hose.

Peter

[Plantman]

ps fred....it is definitely in the area of the themostat as it is behind/under that u shaped air hose, which i thank you for identifying.

Just can't see it. I will find that sucker tomorrow.

[sixto]

Sorry about that - I thought you meant between the turbo and the block. Of course the water pump and thermostat are on the passenger side of the block.

The lower hose is a 3-way job on my car. Connects the water pump and radiator with a spur to the reservoir. Looks expensive.

Working on the thermostat is no fun in the 603. Just enough room for 15-degree turns of a wrench for one of the bolts. Worse if you're lazy and try to do it all from above.

Sixto
95 S420
87 300SDL

[Plantman]

I am a bit stumped as I pressurized the system(mechanic did) and could find no leak.

He gave me a new radiator cap and said to drive it and see.

This morning I woke up and the leak still exists.

He says head gasket. A small leak that is allowing pressure to build up in the system, causing it to leak out of the tank overflow hose when it sits? Does that sound right?

Is it possible that a leak exists under the air filter housing?

I can't seem to find any evidence.......

If there is a leak, wouldn't it have shown up when pressurized?

[Hatterasguy]

My SDL just did the same thing today. After running it up and down the street then parking it I noticed a couple of drips of coolent comeing from behind the radiator. I couldn't figure out where they came from so I pressurized the system to 7psi and it held just fine. If it ever gets above freezing here I will investigate further.

[Plantman]

I am going to drive it in a while and disconnect the over flow hose from the tank when I come back. This way I can confirm if it is a leak or coming from the tank.

FWIW, I cannot see the end of the hose under the tank, hence the need for diconnecting it at the top.

Will let you guys know.

[Plantman]

Drove it around a bit w/o the hose and stopped about an hour ago. No leak....yet.

I will drive it hard later on and see what goes.

[psfred]

Plantman:

The tank itself can crack, and the coolant level sensor can leak, too.

Peter

[sixto]

I believe the overflow from the reservoir goes into the right fender to a bottle near the passenger door hinge.

Sixto
95 S420
87 300SDL

[whunter]

Hello Everyone
I would pull the radiator and take it to your local radiator shop; a partial plugged radiator can cause issues you listed.

If the head gasket is suspected; connect the cooling system pressure tester, pressurize the system, run the engine at 1500 too 1800 RPM for five too seven minutes.
The pressure should remain the same.
A steady rise that does not exceed the blow off pressure is ok.
A sudden rise in pressure (under 3 minutes) is cause for concern.
Have a great day.

[Plantman]

Sometimes things are not what they seem.

I disconnected the overflow hose yesterday to see if there was pressure buiding up causing it to overflow and nothing.

Drove it around last night and parked it.

Looked this morning and there was a nice sized puddle in my driveway.

Started peeking around and discovered the upper radiator hose was dripping ever so slowly.

Obviously, I had not seen that before and it did not leak from there when pressurized, which raises the question, why didn't it leak when pressurized?

Go figure.

In any event, I am happy it's not the head gasket. Fingers crossed.

[whunter]

Hello Plantman
Sounds like the hoses may be beyond service life.
The OEM hoses are durability tested 100,000. Miles, anything more is luck.
After market hoses are only durability tested 60,000. Miles.
I worked in durability testing.
On my personal vehicles; R&R all rubber hoses and belts every 50K, regardless of what they look like.
The typical miles on my domestic daily drivers when sold or scrapped is 200k or 300k with several 500k.
I expect 1,000,000. Miles from my 300 SD, with a projected cost of $00.12 too $00.19 per mile averaged over 1,000,000. Miles, did it before with company diesels.
Maintenance is what makes or breaks a vehicle.
Have a great day.