When does a Head Gasket need Replacing?

[Alistair Francis]

About one year ago I drained all of the coolant and replaced it with new coolant. I have recently replaced all of the cooling components that attach to the engine, including all the pipes, thermostat and water pump. Basically only the radiator hasn't been replaced. I then put a mixture of new coolant and the coolant that was already in there (about 1 year old) back into the car.

I just noticed a shiny layer on top of the coolant in the expansion tank. I'm guessing this is oil, but it looks clear/white so it's hard to be sure. It's possible that this is just left overs from the coolant system or was somehow contaminated in the coolant transfer process, but now I'm worried I have a head gasket leak.

I haven't noticed a loss of coolant or oil, or any white smoke coming from the car. I also haven't seen any overheating issues. I also don't think the car has a rough idle.

Looking around it looks like maybe this: https://www.blocktester.com/ would be able to confirm my suspicion if there is an issue. I was also wondering if it's worth doing a leak down test or compression test. I don't have access to an air compressor though, so a leak down test might be hard to do.

The 1.9L Zed car has about 155K miles on it. Does anyone have any experience with testing if the head gasket needs replacing or thoughts on what I should do?

 

[t-tony]

Hi Alistair, the block tester type is readily available on eBay etc. and very easy to do. My suspicion is that it just some residue from the other coolant which won't mix in with the new stuff. Hope you get it sorted without too much expense.

Tony.

 

[Alistair Francis]

Hey Tony, thanks for the info.

I had done some coolant pressure tests before and the pressure would always drop rapidly, which also made me think it could be a gasket issue. I just finished changing the water pump though I now see the pressure staying constant. I'm guessing that it is just some residue that I don't have to worry about it. I might do the block tester test just to be sure though, as it seems like that is fairly reliable and easy to do.