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My '90 GXL has been sitting for about the past 6-months due to coolant mixing with the oil. For more details, refer to this thread: https://www.rx7club.com/2nd-generati...l-pan-1159646/ I was planning on tearing into it months ago, but had a number of setbacks thus delaying this job. I finally got to it last week week. Had it towed into the shop and started tearing it apart to remove the front cover. Here's what the oil looked like when I pulled the drain plug.
Looks like the caramel macchiato I ordered from Starbucks the other day.
Everything was going smoothly until the other day, but more about that later. I needed to remove the CAS, but wanted to put alignment marks inside of it first for easier reassemble. As a reference, had to first line up the timing mark on my front pulley with the pointer. Problem was that for the past several years, I wasn't able to find the timing marks on that pulley. Therefore, I was never able to check my timing. I bought a couple S5 replacement pulleys (w/o hub) with the intention of eventually swapping my old one out, but never got to it. So, I took my old pulley off after clearing off the rust, I found two barely visible indentations. I marked those two barely visible notches with whiteout. Lined up the second (i.e., yellow) notch with the pointer. Then, without rotating to e-shaft, wanted to see how the two other pulleys I bought which were supposedly from S5's would match up. Here's a photo of my original pulley followed by the other two.
Right on the what should be the yellow or leading timing mark (5 ATDC).
This pulley's yellow mark is about 3/8" CCW.
This pulley's yellow mark is about 1/8" CW.
How can there by so much variation in timing mark between these two pulleys that are supposed to be from an S5? I think I'll repaint the marks and stick with my original pulley.
Next, I wanted to measure the existing e-shaft end play, or float as some call it, and the e-shaft protrusion before removing the hub. There's no iron material in the front of the engine to mount a magnetic dial indicator base. With this in mind, I bought M8 x 1.25 x 130 mm long bolts from McMaster-Carr to screw into a front cover bolt hole and clamp the dial indicator to the bolt. Well, this just barely worked giving me just enough distance between the hub and dial indicator. I should have bought the next longer size bolt.
So, we get measurements of 46 min to 48 max, which indicates 0.002" end play. Spec is given as 0.0015" to 0.0028". I bought a few extra spacers just in case, but it looks like the original spacer should work just fine. We'll need to verify that during reassembly.
The e-shaft end protrusion can be seen between the hub and shaft.
The e-shaft end protrusion measured to be almost exactly 2 mm. The spec for e-shaft end protrusion is given as 2.44 mm or 0.0961" max. I wanted to measure this just for reference.
Up until yesterday, this job was progressing smoothly. Then, I ran into trouble trying to remove the water pump housing.
The water pump housing is seized to the two leftmost studs. I've tried spraying these studs with WD40 and gently prying numerous times, but had no luck. Then, I tried PB Blaster. I tried prying the housing and pounding on it using a hammer and piece of 2x4, but still no luck. So, it'll be sitting until next Tuesday and hopefully the penetrating oil will have worked its magic. I'm thinking about removing the two rightmost studs, which are uncorrupted and trying again. I'm thinking of using a propane torch and heating near the seized studs. I'm holding off on that until the last resort. I'll need to replace the studs and other rusty fasteners anyway. I just don't want to damage the housing, but it might come to that in the end. Any suggestions on how to remove this piece?
I cannot get the front cover completely off until the water pump housing is removed. At least, that's the way it looks so far.
I was able to push the front cover aside a couple inches and peer inside at a freeze plug. Here is what I observed.
Wow, looks like a small hole in the 20 mm freeze plug!
I was able to move the front cover enough to get my hand in there with a small screwdriver. Sure enough, there's a small hole in the small freeze plug. A little $2 part caused me all this grief! There have been a few threads on this same topic in the past. At least two of them had the problem with the small freeze plug rusting out over time. If I correctly recall, these engines have about 8 freeze plugs in total. Three in the front iron, four in the rear iron and one in the center iron ranging in sizes from 20, 25 and 30 mm. Wondering why most of the reported cases are always the 20 mm plug under the front cover? Maybe due to the harsh environment on both sides of the plug? Maybe defective plugs? I already had bought replacement freeze plugs from Mazda. I also bought a set from Melling, which is a well respected US manufacturer. We'll use which ever ones appear to be more durable.
I'm just looking forward to finishing this job and getting the car back on the road. I'll keep you all updated on my progress.
How can there by so much variation in timing mark between these two pulleys that are supposed to be from an S5? I think I'll repaint the marks and stick with my original pulley.
there was a member here for a while, named Karack (then Rotary Evolution), he posted on this issue many times, so i became aware of this years ago through his posts. he cautioned against just getting a pulley and using it. however, i can't remember if his posts included variations within the same series. thank you for documenting this. i think it's very important ... a little frightening, even.
there was a member here for a while, named Karack (then Rotary Evolution), he posted on this issue many times, so i became aware of this years ago through his posts. he cautioned against just getting a pulley and using it. however, i can't remember if his posts included variations within the same series. thank you for documenting this. i think it's very important ... a little frightening, even.
Agreed. These are mass production parts. How can there be variation between them?
Apparently the hub and pulleys are matched sets. So in theory, as long as a hub and a pulley are matched, it should be accurate. It still makes me nervous though. Even though I have a probably matched set, these cars are old enough that there's really no way to know.
I also don't know why Mazda would leave this much variation in the first place. Every e-shaft is precision machined and should have the keyway in the same place, right? So they could just use similar tolerances for the hub and pulley and it would be fine.
It's very frustrating, and I'm guessing in boosted applications mismatched pulleys have led to more than a few lost engines. The stock timing marks are -5 yellow and -20 red which makes 15 degree split, so if the 3/8" measured earlier is equal to approx. 1/2 the distance between the marks, that is a 7.5 degree slack in the static timing. And 7.5 degrees are quite a lot.
Apparently the hub and pulleys are matched sets. So in theory, as long as a hub and a pulley are matched, it should be accurate. It still makes me nervous though. Even though I have a probably matched set, these cars are old enough that there's really no way to know.
I also don't know why Mazda would leave this much variation in the first place. Every e-shaft is precision machined and should have the keyway in the same place, right? So they could just use similar tolerances for the hub and pulley and it would be fine.
It's very frustrating, and I'm guessing in boosted applications mismatched pulleys have led to more than a few lost engines. The stock timing marks are -5 yellow and -20 red which makes 15 degree split, so if the 3/8" measured earlier is equal to approx. 1/2 the distance between the marks, that is a 7.5 degree slack in the static timing. And 7.5 degrees are quite a lot.
Correct, the e-shaft is precision machined with the key-ways all in the same position. All 2nd Gens use the same e-shaft with p/n N326-11-D00C. The hub is also precision machined to match the e-shaft for that specific series car. So, I would expect that the pulleys are marked to match the hub. I can buy from Mazda an S5 hub/pulley set (p/n N350-11-400B) and I would expect these parts to be all identical. I wouldn't expect any differences between multiple hub/pulleys having the same p/n N350-11-400B. So, I don't understand why the variation in timing marks for the hubs that I bought. I requested S5 pulleys and the sellers assured me that they were for an S5, but I cannot verify that with any degree of certainty. I do know the S4 and S5 had different rotor housings with different spark plug hole locations. Therefore, the timing marks on the pulleys would also be different for S4 and S5 engines. It's confusing for me too.
I requested S5 pulleys and the sellers assured me that they were for an S5, but I cannot verify that with any degree of certainty. I do know the S4 and S5 had different rotor housings with different spark plug hole locations. Therefore, the timing marks on the pulleys would also be different for S4 and S5 engines. It's confusing for me too.
I don't think the timing marks would be different from S4 to S5. I could be wrong, but TDC is in relation to the position of the engine when rotor one is at the top of it's compression stroke (stroke isn't the right word here, but it's close enough). The spark plug moving definitely affects the ignition timing but I don't think it would affect the static timing of the engine itself. So if the leading plug is firing at 5 degrees ATDC, and the plug moves from S4 to S5, it's still firing at the same "time" relative to the rotation of the engine. It's just that it's in a different spot, so that will have some effect as if ignition timing was advanced or retarded by that many degrees. The number in software and on the pulley doesn't change but in practice it would change the timing.
Or maybe I'm wrong. Between TDC, leading & trailing ignition, and primary and secondary injectors (both of which are full sequential from the factory), there is so much "timing" stuff going on in a 13B that it boggles my mind.
It's just a weird choice for the pulleys and hubs to be this way. Mazda put a lot of time and effort into everything else, but for some reason decided that pulleys and hubs could have like 5-10 degrees of variation and this wasn't an issue for anyone.
I was actually considering trying to make a post on this topic, but does anyone here know what the position of the keyway in the e-shaft is with relation to TDC? Because in theory this means one could use a degree-wheel and check against that to determine how accurate their hub is. It's a pain to disassemble the stack that far, but if you're in a position like Hot_Dog where the engine is already apart, it would be good to know.
I don't think the timing marks would be different from S4 to S5. I could be wrong, but TDC is in relation to the position of the engine when rotor one is at the top of it's compression stroke (stroke isn't the right word here, but it's close enough). The spark plug moving definitely affects the ignition timing but I don't think it would affect the static timing of the engine itself. So if the leading plug is firing at 5 degrees ATDC, and the plug moves from S4 to S5, it's still firing at the same "time" relative to the rotation of the engine. It's just that it's in a different spot, so that will have some effect as if ignition timing was advanced or retarded by that many degrees. The number in software and on the pulley doesn't change but in practice it would change the timing.
Or maybe I'm wrong. Between TDC, leading & trailing ignition, and primary and secondary injectors (both of which are full sequential from the factory), there is so much "timing" stuff going on in a 13B that it boggles my mind.
It's just a weird choice for the pulleys and hubs to be this way. Mazda put a lot of time and effort into everything else, but for some reason decided that pulleys and hubs could have like 5-10 degrees of variation and this wasn't an issue for anyone.
I was actually considering trying to make a post on this topic, but does anyone here know what the position of the keyway in the e-shaft is with relation to TDC? Because in theory this means one could use a degree-wheel and check against that to determine how accurate their hub is. It's a pain to disassemble the stack that far, but if you're in a position like Hot_Dog where the engine is already apart, it would be good to know.
Apparently, the hubs/pulleys are different for S4 and S5 because they have different part numbers: 86-88 Rx7 Eccentric Shaft Main Pulley (N326-11-400C) and 89-91 Rx7 Eccentric Shaft Main Pulley (N350-11-400B). Don't know why, unless the pulleys are different sizes.
I was searching on this topic yesterday. Somebody posted that the position of the trailing plug hole was different for the S4 versus the S5. Also, I read that when the keyway is on the right hand side (i.e., 90 deg CW where straight up is 0 deg), than number one rotor is at TDC. Here's a post on this topic.
Apparently, the hubs/pulleys are different for S4 and S5 because they have different part numbers: 86-88 Rx7 Eccentric Shaft Main Pulley (N326-11-400C) and 89-91 Rx7 Eccentric Shaft Main Pulley (N350-11-400B). Don't know why, unless the pulleys are different sizes.
I was searching on this topic yesterday. Somebody posted that the position of the trailing plug hole was different for the S4 versus the S5. Also, I read that when the keyway is on the right hand side (i.e., 90 deg CW where straight up is 0 deg), than number one rotor is at TDC. Here's a post on this topic.
The manuals don't indicate any difference in timing between the two series. If I had to make an educated guess, Mazda decided for some reason (emissions most likely) that the split should be globally increased or decreased. So maybe they moved the trailing plug lower to decrease split or something. Again, this wouldn't matter in software since the plug is still firing at the same time relative to rotor position, it's the plug itself that has moved. But it would some sort of effect on the actual combustion.
That doesn't explain the different part numbers though.
I had always wondered why the Racing Beat underdrive pulley is integrated with it's hub, but it makes sense now. You can't make a pulley that bolts to the stock hub and is accurate since the bolt holes have variance in them.
Unfortunately I don't want to underdrive my accessories (I am already using too large a pulley on my alternator which compromises charging at idle). I'm thinking the best thing to do when I turbo swap is get a spare hub & pulley of mine and rig up some way to confirm that 5ATDC is actually 5ATDC.
The S4 had a problem with the trailing plugs not firing so the S5 trailing plugs were moved closer
to the leading plug. The S4 also had a problem with high exhaust temps which was corrected in
the S5, but couldn't say for any amount of certainty that the correction was the result of moving
the tailing plug location, or that the high temps were just the result of the trailing plugs not firing.
Back in shop today after a 2 day holiday break. After wasting over 2 days trying to remove the water pump housing (WPH), finally had success today. Used plenty of penetrating oil with a stud extractor and a short (~7") ratchet wrench. Just took my time and the 2 studs finally broke loose.
Was considering just cutting the studs with a cutoff wheel. Called Ray Crowe about a new water pump assembly, and he said NLA from Mazda. After that, I went real easy and finally loosen the studs. I consider myself very lucky here.
After the WPH was off, I was able to remover the front cover.
There it is. The $2 freeze plug that caused me a lot of grief. Spent most of the afternoon washing parts. Will replace the freeze plugs tomorrow, clean off all the gasket surfaces and continue washing parts.
In the original engine, that I replaced in 2002, I installed a TII oil pump. I know that I took that pump off before I returned the core to Mazda. I just don't remember whether or not I put that pump into this engine. I know that I have a pump somewhere in a box in my storage area. Is there anyway to distinguish between a N/A and TII oil pump.
Here's the the pump that's now in my engine.
Is this an N/A pump or TII pump? It's been over 20 years since I've installed this Mazda reman so my memory is slightly foggy.
Not much action in the shop today. Spent most of the day inspecting & cleaning parts. Removed the 3 front iron freeze plugs. The 2 larger plugs appeared normal, but the 20mm plug was paper thin. Couldn't remove it intact. Interestingly, there was no rust or buildup behind the 3 front iron freeze plugs. It must have been a defective plug when it was installed. Maybe poor zinc coating? Will install the new plugs tomorrow.
Removed the front stationary gear to inspect the bearing. Actually, the bearing looked quite good considering that it has over 163k miles on it.
Still awaiting delivery of various hardware from Ray Crowe, Mazdatrix, BelMetric and McMaster-Carr. Will keep you posted with updates as they occur.
As far as I know, all e-shafts have the keyway in the same position. The only way there would be different marks are: They moved the indicator on the front cover, or they changed the bolt locations on the front hub and pulley.
TDC (compression) front rotor is the keyway at the 9:00 position. There are two TDC's and two BDC's on a rotary engine.
Last edited by TonyD89; 06-02-23 at 05:03 PM.
Reason: Clarification.
Installed new freeze plugs in the front housing yesterday. The two larger plugs are 30mm and the smaller one is 20mm. I used the QualCast plugs rather than the Mazda plugs. The QualCast plugs appeared to have more uniform quality zinc coating, were slightly thicker and were made in the USA.
Plugs were a bit hard to get to with engine in the car. I used a socket slightly small than the OD of the plug and gently hammered them in. I lined the circumference of the plugs with VibraTITE 550, which is anaerobic retaining compound designed to be used on freeze, core, and cup plug applications.
I next replaced the oil cooler mounting brackets. Unbeknownst to me, the right hand side mount was broken and the oil cooler was hanging on that side. These were the original mounts. So, they were over 33 years old and had over 376k miles on them.
According to the FSM, the oil pressure control valve spring in the front cover is supposed to have a standard free length of 73.0 mm (2.87 in). Mine measured slightly under spec at 72.6 mm. So, I ordered a new spring from Atkins. I also ordered two of Atkins' shims for this control valve. They said that they use two of these shims on all of their engine rebuilds.
While inspecting my bearing plate, I noticed that there was some pitting on one side where the Torrington bearing makes contact. The Torrington bearings appeared to be okay, but replacement bearings have already been purchased. Not sure how this occurred. This bearing plate was part the Mazda reman that I bought in 2002 and has over 163k miles on it. It might have been due to metal fatigue of the plate given its age and usage.
So, I also ordered a new bearing plate from Atkins. Other than that, I'm still awaiting delivery on parts. Expect NuCar Mazda delivery tomorrow and Atkins Rotary delivery next Monday.
Not much progress in the shop yesterday due to still awaiting parts deliveries. Other than more parts cleaning, I did start removing and replacing a few coolant hoses. I also replaced the oil filter pedestal o-rings. The coolant hose that goes from the heater to the engine is one that I am replacing. The connection on the engine side doesn't look to be in too good shape.
Probably is solid enough shape for me to reassemble the engine, but it will need to be replaced at some later date. Is this coolant connection replaceable? Does it have a Mazda p/n?
I replaced the oil filter pedestal o-rings. Been putting this off for a long time, but turned out to be much easier than I expected.
I was just wondering if I installed that bracket on the oil filter pedestal correctly? From some reason it doesn't look just right. Does it need to flipped over?
On an unrelated note, since I did have some downtime while waiting for my parts orders, I did replace the bushings in my anti-sway bar links. A number of years ago, I did the S5 to S4 control arm "upgrade" allowing me to replace my ball joints. So, I am using the S4 links. The original bushings in those links were badly dry rotted. I had bought Energy Suspension 9-8134G polyurethane bushings awhile back. I finally got around to installing them. I initially tried pushing the old bushings out with a vice and appropriately sized sockets, but that didn't work too well. So, I burned them out with a propane torch. The new bushings were tight, but I was able to press them in by hand or sometimes with the help of a vice. I also ordered from Energy Suspension the grease-able polyurethane mounts and brackets for my Eibach anti-sway bar.
Probably is solid enough shape for me to reassemble the engine, but it will need to be replaced at some later date. Is this coolant connection replaceable? Does it have a Mazda p/n?.
it is just pressed in, so in theory its replaceable. no separate part number from Mazda though
05-28-23, 10:16 AM
