xr1ckx

Hello, i need some help trying to figure out where I'm losing coolant. I lose about a half inch from the reservoir every 3 days I drive my 2007 Scion tC. I do not have any visible leaks, no puddles under car and I don't have any issues while driving, no overheating.
I had my head gasket replaced 3 years ago and a new water pump at the same time as well as a thermostat. Drove it for 3 years no issues at all then recently noticed the loss of coolant. couple weeks ago I installed a new radiator, radiator cap, new reservoir,
new lower radiator hose and thermostat. i used florescent dye and a blacklight and can't find any leaks still. Check the spark plugs and no signs of a leak. No white smoke in the back and no bubbling in the reservoir. what could possible be wrong that I'm losing
coolant slowly. I drive from SD to LA once a week/2 but I've notices even driving locally I goes down.

I had my mechanic look at it and my heater core was leaking in my front seat floor area so he bypassed my heater core a few months ago to where my coolant no longer flows through that system (I no longer have a heater). So I can't imagine that's the issue.

Anyone have any ideas as to why I'm my car is consuming coolant?
Thanks for the help. if anyone had this issue let me know. Any ideas help.

xr1ckx

anyone ? ill take any information. thanks

bbsciontc

Couple things you can try:

1 Have the cooling system pressure tested by a reliable mechanic.

2 Check the oil for any signs of coolant contamination, and the coolant for any signs on oil contamination. A leaking head gasket can cause cross-contamination.

3 You can use as scope to look at the tops of each piston through the spark plug holes. If you notice that one piston or perhaps two adjacent pistons are cleaner than the others (less carbon deposits), that may suggest that coolant is seeping past the head gasket and into the cylinder. This can have a "cleaning" effect on the carbon deposits.

xr1ckx

bbsciontc

I meant to remove the spark plugs,insert a scope in the hole and look at the tops of each piston. If coolant is leaking into the cylinder, it may "clean" the top of the piston in the affected cylinder (s). Just because the HG was changed, doesn't mean it couldn't leak again. Some of these engines have issues with the head bolts stripping, causing the head to lose tension leading to gasket failure. Not super common, but there were a few cases.

Y2KG20

He should be ok if the engine hasn't been changed out. 2006 and down have the short threaded blocks that have problems on the center cylinder bolts pulling the threads out of the block. 2007 up have different height engagement, a lot more threads and different head bolts to address that issue.

I would just do a hydrocarbon test on the radiator. If it doesn't pass that and it is the head gasket either A:they didn't do it right or clean it properly or B:The head and or block deck may be warped. C: Crack in the head

I had the same problem with one of my personal cars doing the exact same thing. I kept telling myself it had to be a small leak somewhere since it was using about 1/2 gallon a week (about 300 miles) but when I kept looking for traces of water/antifreeze residue there was nothing to be found. The car ran fine (actually was putting 20psi boost on it still) just an irritating fluid consumption problem. It ended up being the head gasket. Lucky I had another engine in the garage built and ready to go in it.