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Hallo all
i have my 92 fd for almost 2 years now. and the first year i broke 3 engines. The interesting issue is that none of them broke from normal issues like detonation or fuel starve or tune etc. all breaks were unusual (even strange paranormal ;-P issues)
let me explain.
1st MOTOR JDM OEM
i got the car on December 2015. it had engine issues thats why it was in a parking spot for the last 10 years. the car had a brand new jdm engine installed back in 2005 from the previous owner . but it never worked. it was pinging LOUD even at 0.3 bar (4psi) and low rpms. you would hit the gas and over 3000 rpm you would listen to pebbles in the can pinging noise even from the drivers seat. it was creepy!!! the car was driven like that for 15.000klm in these 10 years (although with low boost). and it didn't break . the previous owner started to believe that it wasn't detonation because with such loud pinging it would surely have broken all those years. so he said that maybe it was something metal in the turbos clicking or a heat shield etc. But i couldnt beleive that . even the power fc commander knock sensor graph would skyrocket at 170-190 KNOCK !!! when this sound occured!
so i started debuging the issue. tried a new VERY VERY SAFE tune . whatever i did didnt change anything. even with very very low timing a lot of fuel and 15 split the pinging was the same. so i started searching for a mechanical issue. tried new pump , changed coils , sparks , spark cables . nothing.
then i had a eureka moment. reading through this forum i found an issue some people had back in 90s with the coil pack cable. its a small cable with 3 plugs that connect to the coils one plug that connects to the engine harness and one ground cable. i noticed that mine didnt have the grounding cable. the truth is that mazda released a renewed cable that had the grounding internally. but mine looked like it was the old one with the ground cable BUT had the ground cable cut off.
so i changed this cabling and VOILA! the engine was resurrected. full power was back again and there was no more pinging. SUCCESS!!
but the 15.000klm of heavy knocking had taken their tall. after i upped the pressure to normal stock numbers (10 psi) the engine started behaving strange. shacking at idle etc. so i opened it up for a rebuild.
The lucky thing is that nothing was destroyed , no rotors no housings. the issue was that the rear rotor which probably because of the wiring problem had no spark at all in the trailing plug. thus the rear rotor was black with unbearnt fuels marks while the front rotor and housing were totally clean and almost gold (new rotors have a goldish color from factory. the engine had so low mileage that they were both gold).
now the interesting part , the rear rotor that had the spark issue all those years had all 3 apexes broken in the middle . they didnt brake in small pieces so nothing else got destroyed. When examined closes the reason they broke was that from all this knocking the apex seals were full of small marks like they were hit with nails. small holes and some places they had metal shards like the metal that melts when doing metal welding. they were very strange . they looked nothing like normal apex seals, that torture all those years probably made them weak so when spark was fixed and boost uped the metal of the apex didnt have a chance, so they all broke. its logical and i didnt mind at the time.
So i just replaces apexes with new mazda ones and new seals and closed the motor.
so now for BLOWN motor nr2. i will post it later today as its the weirdest break of all times.
So back to the horror story! I left the story last time when my motor blew because it was working 10 years with great pinging. I was lucky because the rotors and the housings all survived. So i just replaced the apexes with new mazda apex seals, i replaced the orings flanges with mazda and also did a mild street port.
I put the motor in, and it fires up immediately. I had to do 2000km as my motor builder told me to break in the apexes. So the day that i made 2000 km a tuned the car a safe tune for 0.9 bar boost and parallel turbos. i tested for knock ,AFr and everything was great ! the tune was super! and the motor very fast. so i was happy
that night a friend of mine with a gtr R34 visited my city . so he called me and we went for a ride through the city. needless to say everyone that saw us in the streets took pictures and videos. and wherever we stopped people would come running.
look at this video from that night:
if you are bored to see the whole video and the runs through the city (and the engines reviews) skip to the last seconds.
SO in the last minute (36:11 in the video) i mention in Greek that i hear a strange metal noise from the engine. like an exhaust goten unscrewed or like a pulley... i stop to think about it but then the gtr comes next to me and we try to make a pull. and the i hear a cracking noise and the motor loses boost and power, i look at the apexi commander knock sensor and i see great knock for 1 second. i stop the video streaming and manage to limp the car back home. it runs rough and i was sure at the moment that it was broken again. so what happened? the tune was super safe, and what was the weird metal noise?? i tried to sleep that night but i couldnt. a brand new rebuild with 2000km broke with no reason.i waited until the sun rose and run to the car and opened the engine bay to check what had hapened... it took me 10 seconds to see the horror.... :-(
look at these pics. one is from the video of that day, and one is from a later picture. if you can see my BOV (blow out valve) was missing its cover
the valve is this kind of bov
but probably a knock of (the previous owner had it installed). so long story short the cover of the bov had gotten unscrewed, 4 small screws somehow got broken or unscrewed and the metal cover dropped to the floor of the car. it stayed there all through the video and then at the end it found its way back to the crank pulleys , there it made the metal noise i heard as the pulleys threw it around . then when i pushed the gas the metal thing went right to the crank sensors and broke one of them while destroying the second, the car didn't know its timing and thus it boosted with totally wrong timing (maybe +10? + 20?)
i know... :-( noone here had heard of such a grave luck. maybe the live facebook streaming was a bad idea. alot of jealous people over the net...
anyways, i will post a small 15 second video i have of the moment i open the hood in daylight and realize the cover of the bov had gotten in the crank pulley... needless to say i couldnt eat for several days. not because a perfectly fine motor with a safe tune blew from just bad luck, but because after building the first motor i didnt have the cash to rebuild at that time.
for my good luck the motor builder felt my pain so he offered me a totaly rebuild engine for just 1500 euros and also made me offer on payments (4 months time to pay off). so i ordered the motor and waited for motor NR 3 to install on my car.... and the bad luck continues on the 3rd motor...
Anddddd.... engine nr 3. I receive it fresh rebuilded. i kept mine that broke to open up and see what i could salvage and i bought another rebuilded one for 1500Euros.
SO i receive it by transport company. I put it in the car. Everything is ok BUT i dont have enough oil pressure. on idle i have 1.5 kilos of oil pressure and when i raise rpm it should go to 4-5-7 kg but it drops to 1 kg max.
i contact the builder. He doesnt understand whats wrong, he says maybe its my gauge, but i have a second defi oil pressure gauge and it reads the same. he says that i shouldnt worry so much because i do have oil pressure. The problem would be if i had none. BUT i knew that mazda says you need 3.5kilos of pressure at 3000rpm
nevertheless the builder tells me i should drive no prob and do 2000klm to break in the apex seals. when i hit 1000km i went the car for an oil change and oil filter change . I took the decision to rempove the front engione cover to check the oil pump and also to check the oil oring that goes in the metal flange .
the one in the red circle. I replaced it also put an oring in it but nothing changed.
THE thing is that while the car was up i noticed that it had a bump on the oil pan. a clear bump like 1-1.5 cm in on the center of the oil pan. Probably it was made during transportation of the motor.
I mentioned it to the builder and sent him a photo but he sais there was no way that could have anything to do with the low pressure.
so i continued doing the rest 1000klm . when i was at 2200km i rechecked the tune. the car was freaking fast. this motor had a big streetport only in the intake ports , and it had oem exhaust ports. this combination made it raise boost very low , 1 bar at only 3800rpm . and it continued to give power up to 8000 redline. I dynoed it at 400engine hp with a very medium safe timing and 11.4 afr.
i started streetracing some nights. and i was very very happy about it!!!
look some runs!! against 400hp evos . in the videos you can see that i have wheel spins on 2nd and 3rd gears, but when the car got traction it would just pass everything. look how easy it passed the evo. like it was stoped!!
i was really happy with the engine and the car and i forgot totally about the oil pressure problem especially as the builder told me not to worry
so one night i was making some runs with a vbox to time my 0-100km/hour and my 100-200km/h . we did the runs , the car did 8 seconds 100-200km/h .
on the last run i made a 60-200 and the passenger that controled the vbox shouted!! keep up keep up!! go to 300km/h!! lets time this!!! the car can do it easily as i see it!!
so i kept the throttle down... we passed 200.... 230...260.... 280km.... and then i see 300km on the gauge (actually it passed the 280 max and went even lower). the vbox gps counted 278km/h ... and the car looked like it had some more... BUT
sudenly i lost power.... i left the gas... i check the commander for knok.... no knock... so i say wtf? maybe some electrical, and i re hit the gas! AND THEN i see in the commander KNOCK!!!
damn.... anotherone bites the dust....
so ... i stop the car. it doesnt even start...i call the truck and pick it up.
well... after checking the engine from the outside. IT OVERHEATED! all the turbo manifold screws became one with the manifold. and after i took it apart the second rotor had goten so hot the apexes were stuck inside the grooves. i still havent goten them out...
whats crazy is that i strongly beleive that when i lost power the second rotor apexes sealed inside the grooves but hadnt broken as the commander didnt show any noise at all... if i just had left the gas and left the car slow down to 0 and cool maybe they would get out again (when the rotor cooled and the grooves opened) , but me hitting the gas again maybe broke the apexes as they were stuck and i saw the knock noise on the commander.
nevertheless.... after searching why it overheated so much (notice that i have gauges for oil and water temps and they were both normal . water 90C oil 92C so nothing TOO hot.) i found out on the net that actually the rotors get cooled by oil passing through them internally. so the low oil pressure meant that there was not enought oil passing through them to cool them. the builder doesnt beleive this to be the issue but i am sure thats it. both rotors got bulked!! in 2 faces!! i read in here that this can happen with overheating of a rotor.
and by the way when i opened the motor i found out why i didnt have oil pressure...
remember that oil pan bump??
ohhh yesss baby.....
it was exactly on the oil suck tube. it was so deep that it had blocked totaly the tube (the tube mesh ) so the tube could suck only very little oil. ...
.... so i contacted the builder showed him the pics and he semi acknowledged the problem as the transport or his (especially after i asked him about the bump when i saw it) . anyways he offered a free rebuild with only me paying the apex and ruber seals.... and 1 housing and 1 rotor that got destroyed....
the engine twists under detonation and the rotor tips hit the housings, pinching the groove
or
your combustion temps are too high due to lean conditions at high boost which caused the seals to warp(this is easy to verify if you lay the seals on a straightedge)
did your tuner actually tune the engine to the speeds you are getting to? a safe tune in third gear to redline isn't necessarily safe in 5th gear to redline. alternatively you may be having an electrical bleed issue, a pump wiring issue(the bulkhead connector likes to get hot and cause a voltage drop to the fuel pump) or you could have a pump that is straining when under heavy consistent loads.
clearancing the rotors helps eliminate the first problem from occurring, but not the second.
I tune the car my self.
the power fc doesn't let you tune by gear like a modern ecu.
thus I programed on 4th gear at the speed you reach in 8000rpm is doable on the street. I couldn't programm on 5th cause I would never reach redline.
my afr was 11.4 on wot and after 7000 it dropped to 10.8 for cooling. My timing was only 14 and split 12. So it's a safe tune. Also remember I saw no detonation or noise in commander. I am sure that the rotors overheated from no oil cooling and everything expanded too much in there.
remember when I disassembled the.motor all the bolts in the exhaust manifold and turbos had to be cut.. Everything overheated in there and I am sure it was from low oil flow.
I have found 2 threads in here that talked about the same issues from low pressure and overheating of rotors
well, that's a theory, however it's a theory i don't believe.
why i don't believe it is because when in motion, the rotors carry as much oil as they can hold, slinging any excess oil that comes in. ie IMO the cooling effect on rotor oil jetting is minimal because most of the cooling is done to the inner surfaces of the rotor and merely bleeds to the combustion faces.
some of these things may be factors, however i believe if you are pinning the last failure solely on oil pressure i believe we might be in for a fourth blown engine thread.
there is other important factors at play here, like were you actually monitoring the AFRs during the blown run or are you just regurgitating the numbers you aimed for in tuning? AITs also have a big impact on when your fuel will detonate in the engine regardless of octane rating. think of intake temps as negating your octane, so if your intake temps are hitting 95C+, its like running low octane pump fuel instead of premium.
problems you may not know exist can arise during a single pull, something that only logging can pinpoint. i don't know about you but when i'm tuning to 140 or so mph, my eyes usually aren't pinned to my AFR gauge. so that's something to keep in mind as well.
for seizing exhaust hardware, it happens normally on rotaries, since our EGTs can climb to 1800F or higher. if you are referring to the original hardware, they are inconel and prone to seizure if you aren't using an anti seizure compound.
Low oil pressure can definitely cause overheated rotors; the rotor is primarily cooled by the jets: it's why the jets are there. A 2.2 mm orifice of heated oil at 100+ psi with centrifugal force as well moves a ton of oil; so much so that when the oil pressure is increased even higher for race engines, smaller oil jets are installed.
I am surprised your bearings and eccenturc shaft aren't destroyed, or any bluing of the end plates.
my AFRs are stable always. and my air intake temps are low because i have a huge intercooler . Also oil and water temps are great because i have a huge koyo water rad and 2 oil coolers. in general i have no overheating issues even in traffic here in Greece. These days we have 38 C ambiend and the car can commute even in traffic with no overheating . 90C max oil or water when in traffic
06-23-17, 09:28 AM
SUCCESS!!
