Slow coolant leak?

So I recently got a new rad fitted this year -- Essentially saw missing coolant, dragged it 100 miles back to my garage and within 2 pressure tests the radiator blew up from the bottom through corrosion. 4,500 miles later, I've checked my coolant and I've noticed it had gone down a slight bit, maybe half an inch from the top, it's not just stuck in the engine somewhere because I've shaken it around, parked it level etc.

It has gone slightly lower than when I last saw it a few weeks ago, I'm convinced I've had a small leak but I can't see anything underneath. I read about the possibility of the cap or expansion tank splitting slightly and under pressure it bursts out of there.

Since it's not drinking water I haven't topped it up though I am making a 100 mile journey back home on Monday, and I haven't pushed this much since I noticed the last little bit of coolant go missing.

Since I know all the pipes, rad and clips were replaced when the rad blew, I know it's not that, or atleast I really hope it isn't! I've not had chance to look underneath or take a deep look but the usual places are bone dry / clean.

Anything I should/could do before I get it in the garage later this week for it's interim service?

Cheers,
Chris.

I've noticed it had gone down a slight bit, maybe half an inch from the top, it's not just stuck in the engine somewhere because I've shaken it around, parked it level etc.

The level should not be near the top. The level should be between the MINI and MAXI marks. This gives room for expansion, while keeping a reserve of coolant.




Overfilling will cause a problem because you loose the expansion space and the coolant gets forced out of the weakest point.

It has gone slightly lower than when I last saw it a few weeks ago, I'm convinced I've had a small leak but I can't see anything underneath.

It takes only a tiny pin prick of a hole to loose coolant, and you probably won't see any evidence of it after the event.





There is quite a bit of coolant pipe at the rear of the engine which is difficult to see.

Anything I should/could do before I get it in the garage later this week for it's interim service?

Confirm the coolant expansion/reservoir was filled to the correct mini/maxi level when the system was refilled after all the radiator and pipes.