5

I have an old Skoda Estelle with its original carbureted engine. It has been working so far. This car doesn't have a thermostat installed.

Timeline:

A few days ago, I realized it was consuming too much water and running a bit hot.

A few days later, I found out the water was coming into the oil sump. It contaminated the oil and made it look like the famous "mayo". I changed the oil.

Today, I drained the oil: no mayo!

Observations:

During a very short trip, the water temp hit 110C. The purge hole in the radiator flows water that is much less than 110C.

There is quicker, more substantial overheating now.

Questions:

  1. First I thought it was bad head gasket, but why does it no longer looking like mayo?
  2. Could this be a clogged radiator?
  3. Any ideas, before I disassemble the engine?

BEFORE AND AFTER :)

before and after cleanup

Aram Alvarez
  • 3,376
  • 4
  • 22
  • 43

3 Answers3

7

Some thoughts:

  • think about interfaces where could coolant and oil mix. The head gasket is one place but there may be another place like an oil-water heat exchanger.

  • Under normal circumstances I would expect the oil to flow into the coolant reservoir and not vice versa due to pressure differentials (oil is usually at a higher pressure than coolant). In your case it seems that the coolant loop is at a higher pressure than the oil loop. Lack of coolant flow can quickly raise temperature and pressure beyond what the system was designed to be at.

  • a few days may not enough for the oil to take on a mayo-like texture and appearance

    OR

    the mayo effect only occurs at very high temperatures. 110 deg C isn't hot enough for that to happen

  • the lack of coolant flow through the radiator could be due to a clogged radiator or a failing water pump (eroded impellers, leaking seals). As there is no thermostat on this vehicle that is one less failure mode to worry about

Zaid
  • 39,276
  • 50
  • 151
  • 294
4

Alright! Mistery solved, engine was overheating because several events:

a) it was passing water to the oil sump because the head gasket got damaged, because:

b) two missing bolts in the head! One was broken inside its hole, the other got the hole threads damaged

c) passing water to the oil (and vs.) made the water sticky, attracting more dirt, because:

d) the previous owner used tap water! so from cylinder 3 to 4, the block got so much SOIL (yes, soil!) that made water impossible to flow, making the engine to overheat, and we go up to the point a) in this list :)

Today I took the wet cylinders out. Lots of soil after #2 towards #4. #4 was epic, like a boot sole from an outdoors walk under the rain hehehe. Even the cam followers for that piston had soil inside!

Aram Alvarez
  • 3,376
  • 4
  • 22
  • 43
-1

You need to check the liner protrusion from the surface of the block if there's not enough protrusion the head gasket and head will not give q good seal when torqued down and the gasket will blow again the liners can sink when the engines overheat and seals determinate leading to oil and coolant in sump

Nge
  • 1