Loosing Coolant

[n/a]

Beginning to discover the problems with my recently aquired 230SL. Despite assurances from the previous owner I've noticed that the coolant water needs topping up every copule of days.

I had a similar problem with my other car a couple of years ago which was loosing coolant and had steam coming out the exhaust. I removed the cylinder head to find a small crack which was welded and then had the head skimmed. It has run ok since.

I am wondering for the 230 if it could be just the head gasket. Although there is no noticable steam, the oil level is very high and it may have some water in it. Any suggestions on diagnosis and remedies before I start on exploratory surgery?

Tim
1965 230SL
1965 Sunbeam Alpine Mk IV

[ja17]

Hello Tim,
Remember that the coolant will expand when hot. The normal level for the coolant when cold is about an inch or so down in the coolant tank. If you are filling it to the very top it will simply expand and go out the overflow when hot and return to the lower level when cold. Hopefully this is the case. Condensation during storage and cold starts can also add small amounts of moisture to the engine oil.
Antifreeze should be changed every two or three years, it will turn acidic and eat away at the aluminum cylinder head and such, eventually causing an internal coolant leak. Of cousre overheating can cause the head to warp and/or the head gasket to fail. Check to see if the cooling system pressurizes too fast after start up (sign of a head gasket failure). Coolant in the oil or out the exhaust is another sign. A compression check can sometimes pinpoint headgasket failure. Hope it turns out ok.


Joe Alexander
Blacklick, Ohio

[n/a]

Thanks Joe

I typically only fill the expansion tank to 1" below full to allow for expansion. There is however a very noticable drop in the coolant level after 2-3 days of driving. I have yet to monitor if there is coolant overflowing after the engine is fully warmed up, though I think this is unlikely.

I live in Singapore where the temperature never drops below 22 Degrees C even at night, so we never use antifreeze here, in fact I've never even seen it on sale.

Your point about storage might be valid as I belive the car may have been sitting unused for a few weeks before I bought it. I had planned to an oil change anyway, so I'll monitor the situation afterwards.

Thanks for the advice


Tim
1965 230SL
1965 Sunbeam Alpine Mk IV

[George Davis]

Tim,

it could just be a small leak, but since you don't have antifreeze, the water will just evaporate and may not leave enough residue to help you find it.  A good radiator shop should be able to pressurize your cooling system, and then you/they can look around for water weeping out.

If no external leaks are found, a leak-down test (each cyliner is pressurized and leakage is monitored) can help pin-point head gasket leaks, leaky valves, rings, etc.

George Davis
'69 280 SL Euro manual

[ja17]

Tim, even if you are not using antifreeze, be sure to use an anti-corrosive additive. Otherwise your engine will slowly eat itself away from the inside out!

Joe Alexander
Blacklick, Ohio

Joe Alexander
Blacklick, Ohio