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Got the oil cooler line project wrapped up. Will just have to prime the lines and start the engine sometime this week. So much cleaner now, cant believe how bad my lines were in comparison. Feeling good about it, never completed a project this large before.
well you might not want them to be too clean ... a light coating of grease or gear oil on all the metal parts might not looks so good once sand and dirt builds up, but better than rusting them out again. At least that can be cleaned off if you need to do maintenance etc.
well you might not want them to be too clean ... a light coating of grease or gear oil on all the metal parts might not looks so good once sand and dirt builds up, but better than rusting them out again. At least that can be cleaned off if you need to do maintenance etc.
Shouldn't be an issue, the car is a fair weather car only now. No snow or rain and it is garaged and taken off the road over the winter.
Well good news and bad. Got the oil lines primed and the engine started. No leaks, no issues there. Then performed a compression test on the motor...
Front:
Rear:
Gotta say, I'm a little surprised. I had a dealer done compression test a few years ago and the numbers were in the high 7's and low 8's, these were all low to mid 6's. Ill try to find the paperwork tonight to compare. I even performed this test 3 times per rotor just to see if there was any change, every time it was within about 5 PSI on each face. Feeling disappointed...
Well good news and bad. Got the oil lines primed and the engine started. No leaks, no issues there. Then performed a compression test on the motor...
Front:
Rear:
Gotta say, I'm a little surprised. I had a dealer done compression test a few years ago and the numbers were in the high 7's and low 8's, these were all low to mid 6's. Ill try to find the paperwork tonight to compare. I even performed this test 3 times per rotor just to see if there was any change, every time it was within about 5 PSI on each face. Feeling disappointed...
I feel like compression tests are more finicky than I had assumed by reading online. Go for a decent drive, run it hard, then immediately take a few readings back to back and consider the final test your results. The people who sold me my tester recommended testing / cranking a few times consecutively to loosen the seals back up for a good reading.
I feel like compression tests are more finicky than I had assumed by reading online. Go for a decent drive, run it hard, then immediately take a few readings back to back and consider the final test your results. The people who sold me my tester recommended testing / cranking a few times consecutively to loosen the seals back up for a good reading.
I didnt run the car hard before the test, but I did do multiple tests. I tested each rotor 3 times, each time only getting a difference of between 5 PSI per face. There is a couple more items I need to address before doing an Italian tune up, then Ill re-test at that point under those parameters. Not sure it will matter, but will be interesting to see.
well it probably makes the usual 170 - 180 rhp that most street RX8s do and likely still feels good. Just don’t go jump into one making 220+ whp and you likely won’t ever know the difference.
Well after feeling sorry for myself for a couple days about the motor's low compression, Ive just decided to soldier on. The whole point of taking on these projects was to learn to do things Ive never done before. This weekend I wrapped up the air pump delete the best I could. I couldn't get the bolts off the manifold for the life of me, so I just put the LRB delete plate over the pipe that goes up to the check valve. It's temporary, but doesn't leak.
I also did some body work, removed all the rust with a wire wheel and a power sander and sprayed it down with rust reformer. I'm going to do a quick cheapo fiberglass filler repair just to pass inspection this summer, then over the winter I'm planning to cut it all out and weld some new metal in. I've only welded once or twice before, so that will be mostly new to me. Luckily a friend of mine has a welder and has offered to let me use it.
The front brake calipers are original to the car, so 15 years old. The passenger side was sticking, and they are both in pretty rough shape. Time for a change, went with Cardones with the extra rust prevention coating after seeing some positive feedback on them elsewhere on this forum. They will be going on this week, I'll take some more pics of the rust clean up then also.
After welding be sure to spray some cavity wax behind or inside the area you welded so it doesn't rust there again.
Interesting, never heard of that stuff. I was planning to just use the rust reformer inside the cavity once I grind everything down and cut everything out. Guess this stuff would be better? Or would you use the cavity wax over the rust reformer?
Anyhow, I got the passenger side brake caliper, rotor, and pads replaced. Pretty straight forward, only got a little snagged on a few things. Drivers side tomorrow, hopefully it will go more quickly and then I can get the brakes bled and ready for a test drive.
Got started on the drivers side today, the one that was sticking. I think I found the problem, the piston was an absolute rusty mess. I'd be surprised if it was even working properly.
On a negative note, the threads on the bracket on the replacement caliper are not accepting the factory bolts. They seems like they weren't tapped correctly, I cant get the factory bolts to catch at all. They bolt back up to the original bracket no problem, and I had no issue like this on the passenger side. I guess I have a customer service call to make...
Rust reformer is good but you can use this wax with a long spray hose and nozzle inside areas that are otherwise unreachable. You definitely don't want to get it on surfaces you would ever touch as it's nasty to get off your hands.
Rust reformer is good but you can use this wax with a long spray hose and nozzle inside areas that are otherwise unreachable. You definitely don't want to get it on surfaces you would ever touch as it's nasty to get off your hands.
Interesting, I will definitely keep it in mind when the time comes.
Got some more work done this weekend. Received the replacement caliper in the mail on Friday, and I didnt have any further issues with that. Just annoyed I had to shell out the extra money to get the new part before returning the old. Went for a drive today and verified the brakes are all good, and what a difference it makes! First time doing a full brake bleed also. The brakes are great, Im sure they will improve with proper bedding. The only thing left for now is to finish the body work on the passenger side so I can get the car inspected this summer. Pic from today's lunch time drive, needless to say Im loving working from home.
Was poking around at rebuild options tonight and came across this from Kevin at RR. I guess my compression scores really aren't as bad as I thought, even though they are outside Mazda's spec. According to the FAQ on Kevin's site, I'm still well within "rebuild" spec (this is a Mazda Reman). From his site:
"In my experience most rebuilds utilizing used rotor housings, used irons, etc. and mostly new oem compression seals/springs, will see 90-105psi of compression with an accurate test after break in, with the variation depending on the specific condition of the rotor housing surfaces used in that particular build. In fact a couple years ago I had a customer bring me an all original, well maintained rx8 with 72k miles for rebuild. The housings looked nice with light wear and were in above average condition. The iron housings had very light wear well within spec. All new oem rotor compression seals and springs were used in the rebuild. I recently did a comp test on that engine after 10k miles of break in and driving. The engine shows about 96psi on the front and 91psi in the rear. It starts cold or hot on the first 2 rotations, idles perfectly, makes good power, and runs like it should with no issues. On a dealer test those compression numbers are failing, a "bad engine" in their view. Does that mean the engine is bad? Heck no. In reality a used rotor housing rebuild isn't ever going to get a whole lot better than that."
Music to my ears, I was deep down the rabbit hole thinking I needed to make a decision ASAP. Seems like this engine is well within the norm with the numbers I posted above. The only concerning number would be the 82 on the rear rotor, but in actuality I only took a picture of the 1st of the 3 tests I did on each rotor. It was up to 87 or 89 (cant remember) on one of the other cranks.
You can always ask the people who made your compression tester what they think regarding results that are better after a few cranks. I had already mentioned something about this but your situation could be different..
ETA: I think that the common response here of "once it's lower than Mazda's fail then get a rebuild" is something that made sense when warranties were a thing but now it's something that we can reference the rest of the rotary community on, even if the Renesis does only make 6 port FC numbers once compression is down!
Each of the three times I tested each rotor the scores came back within 5 or so PSI of each other. I dont think it built pressure over the three tests, but it will be something I will test again down the line. Probably before I store it for winter.
Realistically I'm just happy I read the details from the RR website. I really didnt have that insight before. I assumed if the car was failing Mazda's spec then the engine would be toast shortly after, seems that's not really the case at all. Even if I paid for Kevin to do a rebuild on the current engine I couldn't expect much better scores than what I already have (unless using new housings). This is a weekend car after all, so if I only get another 20K miles out of it that's many more years of service.
Yeah, like I said previously it’s likely down on power some over a perfect engine, but not awful. Once it starts getting below mid-80 psi overall is when it’s about at the limit. However, the longer you go from optimum the more wear the irons, rotors, and housings are going to have. So you’re looking at resurfaced irons with new rotors and housings for a proper rebuild of this engine at a minimum.
This weekend was insanely hot in PA, upper nineties with high humidity. Anyway, I got the rust repair finished and cleaned up in order to have the car inspected next week. I didnt take nearly enough photos as I was trying to work as quickly as I could early in the mornings before the weather got miserable. Here's how it turned out:
Fender needs a little clean up, but the hole is gone. Happy with it for now.
06-14-2020, 09:26 PM
That area of black under the passenger door is where the rust repair was made.
