TheSamba.com :: View topic - Waterboxer operation post oil cooler OWHX failure

Sat Jun 14, 2025 8:54 pm

Hi All

My 86 has suffered a heat exchanger failure.

It happened early in a run and by the time I discovered it, about 2 qts of oil had entered the coolant system.
That's what it took to get the oil level to "add".

The tip off was the factory over-temp light.
I shut down immediately.
No other indications until I checked the coolant pressure tank and it was full of "milkshake".

It's at a shop 1000kms (700 miles) from home.
They proved the exchanger failure and coolant in the oil, though I don't know how much.
I can get them to replace the cooler, change the oil and flush/clean the coolant system.

So, has anyone seen recovery and operation after this this degree of cross-contamination?

My return options are limited and/or expensive.
I'm wondering if anyone has insight into my odds of making it home under power after the above fixes?

I know the oil will deteriorate the hoses - How fast? Is this an immediate or mid-long-term thing?

The pressure and temps (digital aftermarket gauges) were good until the heat problem arose.
I don't know if that was a fouled (lotsa gunk) sender or the rad gumming up or general lack of cooling properties.

Lack of viscosity/lubricity in the oil system would be the other concern and it's affect on the internals.
Other than the gauges there is no way of knowing if (and/or to what degree) that happened.

Has anyone seen this much mess and the engine survived it?

Thanks

Sun Jun 15, 2025 6:15 am

i've had cars with blown head gaskets that puked oil into the coolant. it is a pain to remove but you can get nearly all of it out. buy a large container of liquid Cascade brand (it really does clean better than a cheaper brand) automatic dishwasher detergent and keep dosing-running while the thermostat opens- and flush. repeat. and repeat. it helps to remove the thermostat so things are always circulating thru the radiator. and letting the system get hot each flush helps also.

Sun Jun 15, 2025 6:23 am

also, can you see any markings on the failed HX to determine if it was OE VW or an aftermarket product?

Sun Jun 15, 2025 9:07 am

This is one of several reasons I eliminated the oil cooler on the 2.1L I installed in my 83 1/2. The cooler has multiple failure modes and the 1.9L does fine without it, so why live with a system that does little or no good and can kill your engine without notice.