I will start by saying, I'm not an accomplished mechanic so my terminology will be lacking. Here is my problem. For the last 3 months, I have occasionally had to add coolant to my overflow tank. I would say about 1/2 cup per week. I bought a cheap cooling system pressure tester. I pumped it up to about 13 psi and it slowly lost pressure. I looked all around from the top of the engine and can't seem to find a coolant leak. There is never a puddle under the car. I put the pressure tester on and turned on the car and let it idle. It didn't spike quickly which I know would indicate a possible crack or blown gasket. I pumped up the gauge with the car running to about 13 psi. The needle was steady but slowly dropped. My oil and my transmission fluid are both clean. I recently changed both and there are no signs of coolant in either. I don't see any white smoke from the exhaust, so i don't think i have a blown head gasket. Where are the places I should look for less obvious leaks? Thanks ahead!

 

Losing that much coolant will be evident somewhere. Common places on some vehicles is in the valley of the engine block, the lower radiator tank (collects and evaporates), and sometimes the bell housing of the transmission can collect coolant depending on the shape.

This type of coolant loss will normally leave a dried white or green (depends on coolant color sometimes) stain/paste around the area of the leak.

Pressure test the pump you have. Without it on the car, pump it up to 15psi without the adapter and see if it bleeds down. Most of these pumps have a quick connect fitting and should not bleed down if not connected to an adapter. Also verify the correct adapter and seal for the radiator neck you have. For this small of a leak, a stone cold test is recommended. Heat in the coolant will skew your pressure readings as the coolant cools off.

Coolant level changes do occur naturally for two reasons:

1: The hot coolant in the overflow will evaporate over time, reducing the level. 1/2 cup per half year is about typical, depending on reservoir size.

2: Changes in temperature affect the volume of the coolant. As the weather cools off, the level in the reservoir will drop slightly. Again this is very minor, about a half cup to a cup from 80F to 35F.

Was any work done recently to the vehicle cooling system? If so, specify what was done. A coolant leak will almost always produce at least a minor odor of coolant evaporating. Smell under the hood for this, and start checking with a flashlight around the radiator hoses, heater hoses, housings, and radiator itself. Also inspect underneath and around the crank pulley. If the water pump leaks, coolant will leak out of the timing cover at that point. I don't remember (I don't think it has one) if your vehicle has a plastic engine under-tray. If it does, it may be catching the coolant and running out as the car drives down the road.

 

Thank you for taking the time to reply. I think there may be a faint coolant smell. Haven't done any work recently. I will check the areas you suggested over the weekend and report back.

 

I'm thinking it may be time to take it to the dealership. I think I see signs of dried fluid in various places but I think it is leftovers from a sloppy job when I had the heater core repaired and the power steering line replaced last year. It's frustrating because I also had a slow leak in my civic. I put pressure on that radiater and immediately found the leaky hose and repaired. Not so easy with the accord. Think it's time to take it to Someone smarter than me

 

A dealership is not going to do any more than I have already with the information I have provided. My best advise to you is identify the area's where dried coolant is present, and document it. Then rinse in off in a car wash, removing as much of the staining as possible.

Continue to drive and monitor the coolant level. After a week or so of normal driving, reinspect for signs of leakage. Most dealerships will do no less than this. In many cases, if they see dried coolant anywhere, they may suggest repairs on the spot because the stain is there. If a sloppy install was done, you need to clean on all the old antifreeze. On firewalls that use fire blankets, this small can persist after several wash cycles in a manual car wash.

You can save yourself a ton of money by doing the steps I have provided. If you end up running to a dealership, why even bother posting? Just something to think about....

 

Thank you for the advice. I really do want to find the leak myself. I just thought it may be beyond my ability. This morning I looked everything over again and re pressurized the system to listen for leaks and couldn't find anything obvious. It takes about 10 minutes to drop from 13 psi to 10 so it's not a quick loss. I don't think it's an internal leak but suppose I need to rule that out for sure. Also I will take your suggestion to clean everything up and monitor. Thanks again for the help.

 

ok, i'm pretty stumped. i have looked at all of the suggested places and can't find any obvious signs of dried coolant. thinking it must be an internal leak, i did a block test. the results of the block were fine, showing no leaks. you mentioned it could be in the v. that's really the only of the places i can't see very well. any suggestions from here? thanks ahead, ashton