Did I blow it up? (NC Miata)

haha. We shall see. Still working late tonight so I'll have to do round 2 tomorrow.  I'm proceeding very slowly & deliberately so I can avoid any costly mistakes. 

It's good to have a backup car!!

I just did the belt/idler/tensioner 2 weeks ago on my 07 while I was replacing the exhaust manifold. Reading this makes me glad that I did it early.

I would probably replace the expansion tank sooner rather than later, they tend to get brittle and fail on their own in the best of circumstances.

So I had some other "life" stuff come up in the interim. 

Got back out this afternoon, drained oil into a gallon pickle jar (the first 3 1/2 quarts anyway...) and the rest into my normal catch basin. 
Also took a splash of coolant into a takeut container and drained the oil filter into that.  It's pretty clear to see coolant in the takeout container. but not even a bubble of it in the pickle jar. So far, best possible outcome. 

I decided to hold off on coolant change until I determine whether I'm replacing the expansion tank. A Mazda part is about $60, an aluminum aftermarket one which holds up to the pressure much better is $225-250. For now, I topped up the coolant and am watching it closely. I may start carrying a gallon of 50/50 mix and a funnel in the trunk... just to be safe. 

Next, I warmed up the car at idle and it came up to about 195 degrees, and held pretty steady there.

Hopped in the driver's seat and took about a 10-mile drive with twistys and straights. The temperature gague on the dash didn't really move, stayed right in the middle. Torque + my Bluetooth OBD adapter gave me a temperature range throughout the trip  from 178-197. Low temps were mostly from hard pulls, so more airflow + faster water pump movement. In general it was solid at 185. 

Back home, I rechecked the fluid and topped it up again. I think I had an air bubble somewhere, but will keep a close eye on fluid level from here. Fluid loss (if any) will likely be expansion tank compromise or a hose / gasket. I was able to gently open the coolant cap using the handle end of pliers and got a satisfying "Pfffft" of pressure release. Top up was minimal. 

Re-sealing everything, I idled the car until hot... at 212, the electric fans come on, and back off at 206, so at this point, everything seems to be golden. 

Will try to update this in a week or two (I may still autocross this at Carlisle this weekend) and close out this particular adventure. 

Sounds great, time to move on!

Congrats

Nice save!

Glad to hear it worked out well, I was rooting for you!

Funny story: I was checking on the vitals of my NC before we took it on Xmas vacation trip this year.  Tried to remove the cap on top of expansion tank and the expansion tank broke off at the cap.  Change of plans: Ordered a new expansion tank before we left town and replaced it when we got back.  Luckily we had a small fleet of cars to chose from for the trip.  

Sounds like the best possible outcome!  I'd plan to keep a close eye on it for a few weeks, but it sounds like you got lucky and it survived.  

In reply to whenry :

"It's good to have a backup car!" ...but a small fleet of them is even better :)

Temps continue to be good, performance good, no fluid loss. 

Autocross this weekend at Carlisle after about 400 miles of use went OK, though AWSX1686 beat me by 2 seconds in his '97... :58 vs 1 minute flat. 

Greg Smith said:

Autocross this weekend at Carlisle went OK, though AWSX1686 beat me by 2 seconds in his '97... :58 vs 1 minute flat. 

So it's been nine months. Over the past six weeks or so I've noticed that the car feels increasingly down on power. There is a particular stretch of road that I do acceleration testing from a stoplight and it seemed like I was down as much is 10%.

The car is also up to 185,000 miles. So it's very handy that I have a compression numbers here from before. I want to head and got a set of OEM NGK iridium spark plugs,  pulled all the old spark plugs and the fuel pump fuse as before. This time I did do testing with the throttle floor. Which may not have been the case previously. Also this time, the car was warm. Last time was doing compression testing in the repair process so the engine had not been running.

 Great news! Compression was 185, 185, 185, 190. Brief test trip around the block with a new plugs, and it appears the power is restored to normal.

You know,when the car starts feeling down on power it is a sign you need to do a 2.5 swap

BlindPirate said:

You know,when the car starts feeling down on power it is a sign you need to do a 2.5 swap

Yeah, that's the ticket! Why change the plugs when you have an excuse to do an engine swap?

Umm, who needs an excuse? Just do it! Think of it as preventative maintenance.

Floating Doc said:

BlindPirate said:

You know,when the car starts feeling down on power it is a sign you need to do a 2.5 swap

Yeah, that's the ticket! Why change the plugs when you have an excuse to do an engine swap?

Umm, who needs an excuse? Just do it! Think of it as preventative maintenance.

I have been telling him he should keep this thing for a while and do the 2.5 swap...

This is a daily that I want to keep as close to factory as possible because I want it to remain drama free. 

My TR7 Spider will get the "one off" toy car treatment. Looking forward to better weather, but woke up to 1 1/2" of snow...