Coolant leak that is a mystery - 99 V6

Okay, hate to ask for help as new member, but this is urgent!

Have had the leak for about 1 month, keeps getting worse. Car is super well-maintained, 135k miles, timing & water pump replaced approx. 25K/3 yrs ago. Leak was initially only noticeable when engine was off, but now leaks while running also. The thermostat was BADLY corroded and dripping coolant, so I changed with the OEM ($40 part) thermostat and gasket. However, leak continues.

Took off TIMING cover only, and belt looked clean/dry....could see a LITTLE corrosion on the water pump...may have been from the drip hole. Passenger motor mount is BROKE, so this leads me to believe leak could be from center of car OR driver's side. I came to this conclusion after jacking up passenger side for several hours -- and leak only dripped from driver's side.

There is coolant EVERYWHERE though! Oil pan = covered. Transmission Pan = Covered. Driver's side undercarriage = covered. I do know for a fact the distributor is leaking oil so this may have corroded a hose or two that I cannot see. And also some of the coolant may be mixed with oil -- it's so nasty I can't really differentiate that mixture.

Any suggestions? Sorry for rant. My pops did the timing belt job and is ace mechanic, but there's only so much he can do 2500 miles away over a phone. Anyone else come across this ****ty of a leak on this gen V6? Please, anything will help. Trying to avoid the "pressure test" that will likely result in mechanic immediately suggesting waterpump/timing job. I can hear it already

Any smoke while driving? Sounds like a severe leak. Could always try UV dye. Try searching the forum too, you're certainly not the first.

Also hit a car wash! The engine sounds like it needs cleaned, so use some spray-on engine cleaner junk.

Then find the leak, it will be much easier once it is clean!

xci.ed6 said:

Also hit a car wash! The engine sounds like it needs cleaned, so use some spray-on engine cleaner junk.

Then find the leak, it will be much easier once it is clean!

Click to expand...

A+ on that!

hondatech forum. more technical

Hey aww i cant say much visually but based on your findings which was vague " distributor leaking oil" my best advice is to start the car. 1 watch temperature needle try to see how long the needle climb to warm up. 2. after car is warmed up lightly squeeze the upper radiator hose and feel if the pressure build up is strong or weak. 3. smell for coolant burning if not look at thermostat housing, radiator, hoses, reservoir and caps for leak. DONT OPEN RADIATOR CAP WHILE HOT!!! 4. Unplug the negative battery terminal, disconnect sparks plug wire in order of steps, unscrew the distributor cap and rub your fingers in it looking for oil, if not screw it back up reconnect spark plug wires in correct order and battery terminal. 5. start the car again let it run and get a timer to see if the fan kicks on and how long it takes to come on. 6. if all cooling system is working correctly. You may have a leaking thermostat gasket or housing was not seal correctly, weak hose clamp somewhere either upper or lower radiator hose, air getting in the coolant system, As for the water pump the rule is: this should be replace with timing belt job but if not you have to replace it again and seal the rea properly. Lastly spray engine degreaser not on the distributor/timing belt but on the undercarriage of the transmission and block to see oil or coolant seepage.

Guys, thank you! But car is still not fixed. Thermostat looks fine...just replaced with OEM and gasket less than month back. Could be leaky hose...though looking less likely. Leak has seemed to back off some since I replaced most hose clamps. Just gonna do pressure test in morning. At very least, needs motor mount, o-ring on distributor, ck engine code diagnosed, possibly new hose, and oil pan gasket. I hate spending money but I love my Accord more

The only compression test you could have done for cheap and quick was to take the palm of your hand and choke the upper radiator hose (x3 times) while the car runs choke-release then wait 5 second-choke-release then wait 5 second-choke-release then wait 5 second let go for good. Again if there's not much pressure (feel of stiffness) then the cooling system have air in it or leak in it. But you don't listen. Bedrock!!! You dint even troubleshoot any of the idea I gave you. Visual inspection alone cant diagnose a leaky cooling system. "FYI" compression test cant diagnose a leaking engine, it only give psi reading of cylinder compression. The best last resort thing to do is pump air in the radiator if you have the kit for that.

And again the advice's you get were not of visual findings so don't expect to get a precise answer. You have to be willing to take our advice to troubleshoot your own problem. getting answers and coming back to say "I didn't see this or a few months back I replace that." The advice you get for free here would cost you at least $50 at your local auto repair shop unless the same mechanic going to fix the problem then you wont pay. Fact

Sorry for long delay. Of course it was water pump leak. A slight leak, at that. Mechanic gave me the old "Who replaced timing and water pump last?" I knew heavy bull**** followed. My father did, and he goes on to tell me that WE (since I helped before moving across the USA and spent last few eves with my aging father) must have reused the old seal for the pump/ My dad makes errors, but since he paid for and pays for any maintenance when I am not close enough for him to fix, I don't see how BOTH of us let that happen. In fact I am not convinced the timing belt was even replaced; For $380 what was I expecting? So finally, I asked him to read codes on CEL and he quotes me $350-400 to clean out EGR. Hahahaha.

Oh well, a sucker is born every day. I respect he needs to make a living, but does he think I look rich AND foolish? Now on to my next project -- repairing ivory leather bucket seats in front to look GREaaatttttt