Is this the sound of an apex seal gone bad?
04-19-08, 03:10 PM
#78
Lives on the Forum
Ray, just to be on the safe side, you'd better read my thread that I posted describing the final weeks of my 12a. I was finally able to listen to one of your videos, and it sure sounds like mine did. I hope I'm wrong, but check this thread out: https://www.rx7club.com/showthread.p...ighlight=knock
If I had torn it down before the apex seal broke, I don't think it would have been rebuildable anyway due to the mileage (213,000 miles). But if your's might be in better condition, then you should consider taking it out of service now before she blows. I hope I'm wrong and your motor is fine though...
If I had torn it down before the apex seal broke, I don't think it would have been rebuildable anyway due to the mileage (213,000 miles). But if your's might be in better condition, then you should consider taking it out of service now before she blows. I hope I'm wrong and your motor is fine though...
04-20-08, 10:43 AM
#79
Thanks Kent, if the symptoms continue I will certainly take that advice and begin the rebuild. Jesse yes I realize there is an official way to measure the OMP output, besides just watching it rise up in the tubes. Just getting lazy I guess.
So here's some more news. Mike and I pulled the carb in the White One yesterday and guess what? Yep the coasting valve was stuck closed. Hmmm.....
Also I found a little bit of antifreeze collecting over the intake manifold, probably not contributing to the poor running (that would be the coasting valve, right?) but since I'm in there anyway it's time to replace the manifold O rings and gasket - an order is going into Mazdatrix today.
While I'm at it I'm doing the same work to the Silver One, turns out its intake manifold is leaking too and everything in there just needs a good cleaning (I like things looking good under the hood). So now that intake manifold is off too, I'll be putting that one back together too when the Mazdatrix order comes in.
I'll take another close look at the carb that was in the White One, it was rebuilt last year and it's still real clean, so it should be alright. When the Mazdatrix order come in I'll put everything back together. If the problem is still there I'll swap in the carb from the Silver One just to be sure it's not a carb problem. If the engine is still running rough it's rebuild time.
And time to put the Silver One on the road. If the White One is fixed, I'll still put the Silver One on the road. That way I can choose which color FB I want to drive each day.
Again thanks for all the feedback and assistance guys, this is a great community. I just wish that Jeepforum.com group was as helpful!
Ray
So here's some more news. Mike and I pulled the carb in the White One yesterday and guess what? Yep the coasting valve was stuck closed. Hmmm.....
Also I found a little bit of antifreeze collecting over the intake manifold, probably not contributing to the poor running (that would be the coasting valve, right?) but since I'm in there anyway it's time to replace the manifold O rings and gasket - an order is going into Mazdatrix today.
While I'm at it I'm doing the same work to the Silver One, turns out its intake manifold is leaking too and everything in there just needs a good cleaning (I like things looking good under the hood). So now that intake manifold is off too, I'll be putting that one back together too when the Mazdatrix order comes in.
I'll take another close look at the carb that was in the White One, it was rebuilt last year and it's still real clean, so it should be alright. When the Mazdatrix order come in I'll put everything back together. If the problem is still there I'll swap in the carb from the Silver One just to be sure it's not a carb problem. If the engine is still running rough it's rebuild time.
And time to put the Silver One on the road. If the White One is fixed, I'll still put the Silver One on the road. That way I can choose which color FB I want to drive each day.
Again thanks for all the feedback and assistance guys, this is a great community. I just wish that Jeepforum.com group was as helpful!
Ray
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04-20-08, 09:09 PM
#83
You right Sam, this is the way in needs to be. 2 7s in every drive. Only mine are going to be white and silver. With matching red leather interiors. And 12As. With rat's nests.
Although I do like that tornado gray. Put red leather in that and you are all the way there.
I got a lot done today, the girls really did need some attention. Here's some photos:
And I still have no idea if I've solved the problem.
05-04-08, 08:18 PM
#84
OK I got it running. I pulled the carb and intake manifold to replace the intake gasket and seals and fix the shutter valve, which was stuck closed, making it the most likely suspect for the "bad apex seal".
I cleaned up the manifold, shutter valve and vacuum valve and I replaced the shutter valve shaft, which had a sheared pin wedging the shutter valve in the closed position.
Then I put everything back together and fired it up. Here's a video of the start up, after sitting for more than a week in sea foam:
Here's about an hour later, after the sea foam had burned off and I'd set the timing and carb idle:
Still needs some fine tuning but I think I'll drive it to work tomorrow and see what happens.
I cleaned up the manifold, shutter valve and vacuum valve and I replaced the shutter valve shaft, which had a sheared pin wedging the shutter valve in the closed position.
Then I put everything back together and fired it up. Here's a video of the start up, after sitting for more than a week in sea foam:
Here's about an hour later, after the sea foam had burned off and I'd set the timing and carb idle:
Still needs some fine tuning but I think I'll drive it to work tomorrow and see what happens.
Glad you were able to make everything work again. Have fun tomorrow.
05-05-08, 11:48 AM
#89
Well OK, it was a little chilly this morning and it wouldn't start from a cold start, so I still haven't had it out on the road. It's acting like it is flooded, probably a vacuum leak or I didn't get all the hoses in the right place when I put the carb back in.
Or, ironically, it might be that the shutter valve is leaking a little - I noticed a weak vacuum at the breather port when it's at idle. I'm not sure if the vacuum actuator that I put back in was the same one that came out, which worked OK until the pin on the butter fly shaft bound up.
I'll check it all over this evening, but the good news is you are right Dave, the White One is sounding way better than it did when the shutter (coasting) valve was stuck and it looks like a rebuild is not in the near future. Back to driving bullet proof 12As that never die and dreaming about that mild street port.
Michael the main reason I want to keep the shutter valve is for gas mileage and emissions. When it's functioning properly it cuts off fuel to the rear rotor, saving a mile per gallon or two on the gas and cutting down on the emissions a bit. Or so I've heard.
When I get everything properly adjusted and cleaned up, I'll post a video to put closure on this episode. Thanks to all you folks who walked me through it, especially Jeff, who intuition turned out to be right on this one. I hope the discussion will be of use to others who might be thinking "is this the sound of an apex seal gone bad?"
Or, ironically, it might be that the shutter valve is leaking a little - I noticed a weak vacuum at the breather port when it's at idle. I'm not sure if the vacuum actuator that I put back in was the same one that came out, which worked OK until the pin on the butter fly shaft bound up.
I'll check it all over this evening, but the good news is you are right Dave, the White One is sounding way better than it did when the shutter (coasting) valve was stuck and it looks like a rebuild is not in the near future. Back to driving bullet proof 12As that never die and dreaming about that mild street port.
Michael the main reason I want to keep the shutter valve is for gas mileage and emissions. When it's functioning properly it cuts off fuel to the rear rotor, saving a mile per gallon or two on the gas and cutting down on the emissions a bit. Or so I've heard.
When I get everything properly adjusted and cleaned up, I'll post a video to put closure on this episode. Thanks to all you folks who walked me through it, especially Jeff, who intuition turned out to be right on this one. I hope the discussion will be of use to others who might be thinking "is this the sound of an apex seal gone bad?"
05-05-08, 12:05 PM
#90
You're welcome. I had the opportunity to hear when a shutter valve was open and closed once, due to a minor exhaust leak on the rear rotor at the exhaust port*. It was educational to hear when it would cycle between open and close states. Plus several others have recently had trouble with the long 1/2"ish rubber hose that goes from the rear secondary runner up to the uh coasting valve you said? Anyway it springs a leak and leads to all sorts of wonderful idle issues.
* It was a 12A turbo rotor housing and one of the funny emissions holes was not fully covered by a thermal reactor type exhaust gasket - I replaced it with an '81-'85 gasket. https://www.rx7club.com/forum/showthread.php?t=638282
* It was a 12A turbo rotor housing and one of the funny emissions holes was not fully covered by a thermal reactor type exhaust gasket - I replaced it with an '81-'85 gasket. https://www.rx7club.com/forum/showthread.php?t=638282
05-05-08, 08:37 PM
#92
OK I think we got it licked. Turns out it was the coasting valve this time (shutter valve last time, for clarification see below, thanks to Jeff's "huh?"):
It was leaking air causing a small vacuum leak. Here's the fix, a cork (marked "W") plugging the coasting valve hole in the breather:
And here's the video of the White One idling down at 200 rpm without skipping a beat, the thing is chugging like a boinger. You can see the cork toward the end:
And here's what's going to work tomorrow, idle set to 750:
I'm going to have to figure out how to test for that vacuum leak before the coasting valve is installed so I can test the three or four used ones I have before putting them in. Or maybe it's just time to plunk down $100 and get a new one?
Anyway, case solved. We should rename this thread "The sounds of shutter valves and coasting valves gone bad"
Sam, I like the red, your 7 is getting a touch of class. Where'd you get those?
It was leaking air causing a small vacuum leak. Here's the fix, a cork (marked "W") plugging the coasting valve hole in the breather:
And here's the video of the White One idling down at 200 rpm without skipping a beat, the thing is chugging like a boinger. You can see the cork toward the end:
And here's what's going to work tomorrow, idle set to 750:
I'm going to have to figure out how to test for that vacuum leak before the coasting valve is installed so I can test the three or four used ones I have before putting them in. Or maybe it's just time to plunk down $100 and get a new one?
Anyway, case solved. We should rename this thread "The sounds of shutter valves and coasting valves gone bad"
Sam, I like the red, your 7 is getting a touch of class. Where'd you get those?
05-06-08, 01:04 PM
#95
I redid the seats with the seat kits from Racing Beat. Sounds like you got the car running great. Why don't you just lock the coasting valve open. I don't know how many of those things I have seen bad. I know you love the stock "apperance", but it would still look stock.
05-06-08, 02:35 PM
#96
Not a chance this one is going to the junk yard Wacky!
Nice looking seats Sam, you've got good taste. On the coasting valve, it's not about keeping it stock, you can't even see the coasting valve and I'm all for mods that increase all around performance. I want the coasting valve because a properly functioning coasting valve should save gas and lower emissions
But for now I've got it blocked off.
Anyway, surprise, surprise, the car's not running again. I just found what is probably the culprit, a bad leading ignitor. When it rains it pours.
Hope I can get it going in time to make the OGTA meeting tonight.
Nice looking seats Sam, you've got good taste. On the coasting valve, it's not about keeping it stock, you can't even see the coasting valve and I'm all for mods that increase all around performance. I want the coasting valve because a properly functioning coasting valve should save gas and lower emissions
But for now I've got it blocked off.
Anyway, surprise, surprise, the car's not running again. I just found what is probably the culprit, a bad leading ignitor. When it rains it pours.
Hope I can get it going in time to make the OGTA meeting tonight.
05-06-08, 11:34 PM
#99
Dave I'll take that coasting valve, thank you! I do want to get a good one in there.
Although I have to say the car ran just fine this evening with the valve corked off on the 50 mile round trip to OGTA (the leading ignitor was toast, I replaced it). Just one big backfire on a long highway deacelleration.
The White One is Back!
Although I have to say the car ran just fine this evening with the valve corked off on the 50 mile round trip to OGTA (the leading ignitor was toast, I replaced it). Just one big backfire on a long highway deacelleration.
The White One is Back!
Last edited by ray green; 05-07-08 at 12:00 AM.
05-07-08, 12:08 AM
#100
Oh yeah, Firebirdslayer was right, there was an exhaust leak. The area around the intake tube on the muffler was rusting out. I switched in a spare muffler in time for the OGTA meeting, took less than 1 hour start to finish. The car is quieter.