Hi,

during these last two months i noticed that my car loses coolant around 800ml or less after a drive from work, it would drop to the coolant level sensor but not more than that and i can hear water sloshing noise from under the dash.

i don't have any white smoke but there is a lot of pressure coming of the thermostat housing when i start the engine and idle.

i also left the car sitting for 3-4 weeks and the coolant dropped just below the coolant level sensor.

I'm using Pettit thermostat which is drilled so I'm not sure if some of the symptoms are caused by the thermostat like coolant overflowing from the filler neck.

anyways, do you guys think its blown seal? if so who is the best engine builder that can build reliable rotary

 

There is no "best engine builder"

You would need to properly diagnose your situation starting with a coolant pressure tester. Losing coolant with no smoke or starting issues is a little uncommon. Keep in mind the stuff doesn't just vanish, it has to go somewhere and if that somewhere is in the housings then it would need to burn off.

The alternative is the coolant is leaking not into the housings but into the oil pan which would explain why you dont have the usual symptoms. That would be easy to check as well.

Go through a standard "missing coolant" diagnostic procedure and you will find your problem. If no coolant can be discovered exiting the engine or the overflow then it would be advised to bleed/burp the coolant system properly and replace your pressure cap.

 

if you are losing a consistent amount of coolant after a drive and it doesn't seem to be going out the exhaust you may have a failure in your overflow line. as the motor warms coolant expands and it flows into the overflow tank. as the motor cools after a run the coolant contracts and the vacuum sucks the coolant back into the motor. if the line has a rupture, or the fitting at the neck is not tight, the motor will continuously push coolant into the overflow but not be able to suck it back in. eventually the overflow tank will fill and coolant will exit onto the floor.

if this doesn't solve your problem, and i hope it will, i would go w FD Auto and do a coolant system pressure test.

 

I tried pressure testing I lost maybe 3-4 psi over an hour period and the only start up issue I have is if I start the car after it has been sitting for few weeks.

i will replace the pressure cap, ast tank and thermostat

 

I have replaced the overflow tank that didn't seem to fix the issue I will replace the ast tank and hoses, but keep in mind I also lose coolant without turning the car on but it takes three weeks

 

Don't worry about the thermostat if your car isn't overheating.

The psi drop you saw was normal. The tool itself leaks no matter how nice it is. When we do pressure tests, we look 1-3psi over 15 minutes. Thats a pass.

Check your overflow for holes and delete your ast. Looking like your motor is fine

 

I had a blown inner coolant seal. First sign was the add coolant warning light. The coolant was being pushed out the weep hole of the coolant reservoir. It’s a small amount gradually. When the car would sit for a day or so one housing would fill with water causing a really rough start with a lot of white smoke. I rebuilt it myself with good results based on watching youtube vids. If you are mechanically inclined, it’s actually not that hard. Also, if you’re adding “water” to constantly top it off like me, don’t let the car sit for a long time before working on it because it will cause a lot of rust inside the engine and be more costly to repair.

 

If you want to do coolant tests, the mishimoto kit (available from summit) is great. I left it on a week and it leaked down 0.5 pound.