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Hey so i just rebuilt my motor and replaced almost everything in the coolant system. Like all the hoses, radiator, ast tank, water pump, I replaced the thermostat before the rebuild with a mishimoto one that activates sooner. I even replaced the caps before the rebuild too only thing I haven’t replaced was the thermostat housing itself. Car isnt overheating the hand on the gauge stays at 9oclock and on my fc commander coolant temp stays between 80-90 degrees celsius. But while the car is running it pushes coolant out from the filler neck on the thermostat housing. I have no clue whatsoever what could be causing this the motor doesn’t even have 200 miles on it yet. Was thinking maybe a faulty cap but literally just purchased one from the dealer and replaced them not even 300 miles ago, was also thinking the thermostat housing neck is plastic and maybe since its the stock housing and has been there for all of the cars life it’s starting to crap out.
Any help at all would be greatly appreciated please someone save me from this heart ache.
*Check the hose running from the filler neck to the overflow and make sure it's not pinched or blocked.
*Check that the t-stat was installed correctly and the jiggle-pin is at 12:00 o'clock.
*Check to make sure you have the spring cap on the AST (if you're running one). With an AST, the filler neck should have the non-spring cap.
* You may have pinched a coolant seal during the rebuild.
Ok so when i checked my coolant levels this morning in the thermostat housing and the ast tank they were both completely full to the top couldn’t even add a drop of coolant so dont know if my mechanic just put to much coolant in the system. You said to make sure the hose from the filler neck to the overflow bottle wasnt pinched or blocked but the hose goes to the ast tank so not sure if that’s supposed to be like that. Otherwise my mechanic is getting me another thermostat, and i went ahead and purchased a new thermostat housing and cap.
I deleted my AST some years ago and mis-spoke...I meant from the AST to the overflow. Regardless, none should be pinched or blocked. Still, can you take a picture of your AST and the line routing?
And you don't have a spring cap on the filler neck....right?
Sorry just remembered you asked for pics of the routing going to post them tomorrow, my water temperature always stays in the same zone never gets to hot but I checked my filler neck the coolant was at the bottom but my ast tank was as full as can be. Im so confused as to why its pushing the coolant out, my car isn’t blowing smoke and its running pretty damn good literally no problems except for this do you think maybe there was to much coolant in the system or should the filler neck and ast tank be full when its cold. Thanks for the help so far though you guys always come through.
When fully cooled down on a completely sealed cooling system, you should perceive just a little vacuum when trying to remove the filler neck cap. And if you watch closely, you can usually see the coolant level drop a few millimeters as the cap is removed. That's normal.
The reason I requested pictures of you AST is that if you look real close at the routing of the lines at the AST in that cooling system diagram, it 'appears' that the line from the filler neck to the AST on your car is plugged into the wrong nipple. The line at the TOP of the AST should run to the overflow bottle.
When fully cooled down on a completely sealed cooling system, you should perceive just a little vacuum when trying to remove the filler neck cap. And if you watch closely, you can usually see the coolant level drop a few millimeters as the cap is removed. That's normal.
The reason I requested pictures of you AST is that if you look real close at the routing of the lines at the AST in that cooling system diagram, it 'appears' that the line from the filler neck to the AST on your car is plugged into the wrong nipple. The line at the TOP of the AST should run to the overflow bottle.
It looks like you might have the Rx7.com AST installed from your picture. If that's the case I would agree with the above that your line is misrouted. I believe the middle nipple goes to the filler neck if I remember correctly. Here is the stock photos from the website. I think all the Rx7 ASTs have the same setup.
was also thinking the thermostat housing neck is plastic and maybe since its the stock housing and has been there for all of the cars life it’s starting to crap out.
Probably not the cause of your problem, but a better filler neck...
^It's a great piece. I have one. But it's more for the guy whose eliminated the AST and would require him to plug or eliminate the nipple on the filler neck housing.
The first pic was when it was at my mechanics house he must’ve rerouted it before giving the car to me. And idk what that is i have to ask my mechanic what he did there. And I ordered a new thermostat housing that comes with the neck conjoined from atkins rotary. Just got home in the car and right down the block from my house i started to take off and the car started to stutter like almost cut power completely and then came back and then every time i shifted the car would do the same thing cut power and then come back. I don’t know if it has to get tuned because im running the base map on the power fc until I break in the motor but it just started acting up like that for the first 300 miles it was running fine.
I know you mentioned the engine was just rebuilt so this is probably not a necessary test, but have you let the car idle with the coolant cap off, and make sure you aren't seeing lots of bubbles or anything?
Sorry about the late response i fixed all the problems the coolant leak was the thermostat housing or the cap replaced both got rid of the problem. And for the stuttering it was the throttle position sensor thanks for all your guys input greatly appreciated you guys are the best. Also i would like to ask i have 550 miles on the break in and i was gonna do a oil change what oil would you guys recommend?? Thanks in advance
Use regular mineral oil during engine break-in period. I'd use 10w-30, the viscosity range recommended by the FSM. (page A-9 and the owner's manual if you have one) for temperatures this time of year.
Thanks just did my oil change tonight used 10w30 when would you guys recommend doing my next oil change at 1,000 miles?? And after i hit 1,000 miles my mechanic wants me to dyno tune my car I feel like that’s alittle to soon but I don’t know was wondering if you guys could give me your opinions thanks a million you guys have been such great help.
Ok so I bumped up my rev limiter to 6k and im going to put another 500 miles on the car im at 1,000 right now. Was wondering if you guys think it’s necessary to tune my car after break in since my car is full bolt on right now. Also when i rev up the car to like 5500 I feel like theres alot of boost coming on was wondering if it was safe to drive like that during the engine break in period.
Yes, have the car tuned. You're running the base map and, apparently, you're not monitoring your boost level. That should be corrected as well. I wouldn't drive it hard until you do.
Yeah i already ordered a boost gauge and water temp gauge once i get them im going to install them im going to tune it tomorrow should be at around 1450ish miles. Thanks for the feedback.
Last edited by Rotary809; Aug 20, 2019 at 10:53 AM.
