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post #1 of 8 (permalink) Old 4-19-17, 17:01 Thread Starter
 
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looking for engine rebuild advice

hello fellow 6'ers

its been a hell of a few days. i made a post awhile back trying to figure out why one of my f2s would intermediately buck and shake but only in gear, stopped (wheels not turning) giving revs. the thing that had me thinking it was clutch/transmission related is while bucking if i pulled it out of gear it would instantly stop.

i know now i was wrong...all wrong.

let me refresh everyones memory and give the history of the car.

i bought the car maybe 2 years ago now with a bad atx. the car had 84k original miles on it when i got it (now has 86k) and the body is in incredible shape for the cars age. it is a 1988 mazda 626 hatchback with the ft2. since i bought it i changed it over to an mtx and it ran damn good (still running). a few months into driving it around i noticed some slight "hiccups" between say 1500rpm and 2500rpm. also one day getting off the highway and stopping at a light i decied to give the car a little rev (car in 1st gear foot on the clutch) and the car shook like crazy, i then got the car home and went crazy looking for the issue. i went from engine mounts, to ignition to the transmission, clutch damn near everthing on this engine is new...it was consuming me and my wallet ...still is lol

so lets fast forward to the other night when i realized i have a bigger problem then a silly little transmission or pressure plate issue. i noticed the harmonic balancer had a slight wobble to it and i had a spare one laying around so i said screw it ill swap it and maybe all my problems will be gone ...again sooo wrong.

after i remved the belts i grabed the balancer and gave it a good yank in and out, what do i feel?
yeah the crank has more play then it should i promise you that, when the balancer came off there were marks on the lower timing cover consistant with the pulley. it was touching. it was in the back of my mind there was a thrust problem but dismissed it thinking of you guys and reading about how solid these bottom ends are and the the damn thiong got 80k on it!! lol. anyway so i got the old pulley off and placed the new one on and of course leave it to me to break one of the six bolts off while tightening it down. i started the car and the crank still wobbled and it actually seems like it made the rubbing worse, not only that now my front crank seal is leaking and i got a broken bolt in the crank now i am scared to drive the car...i plan on getting some new crank pulley bolts and trying again but really lost steam as of right now and my girl already wants the car gone lol i had no idea this car would turn into such a project but it all seems so worth it lol

i am trying to get my stuff together and get the engine out, i am debating on if i should take it apart myself or send it to a machine shop, also wondering if i should have the head done while im at it or leave it alone.i believe the crank should be removed, grinded and fitted with undersized bearings... i obviously dont want to spend a crap ton of loot on the car (too late) but do want it to be reliebable. i believe i could actually fix it if i had the space and took my time (never built an engine) i really dont plan on beefing it up it and some guys may laugh at me but the car is torquie enough for me lol. i am open to advice and look foward to hearing some of your opinions.
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post #2 of 8 (permalink) Old 4-19-17, 21:22
 
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Well I sent you an email, you can post it here to get opinions on my thoughts.

When you say " i really dont plan on beefing it up" what exactly do you mean? the only thing you can do is buy rods with studs which aren't a weak point or needed until making insane engine pressure and record F2T power. Knife edging the crank, boring the block, running wiseco 8.5:1 pistons all weaken the engine.
To me the "beefiest" F2T possible is bone stock with lightly warn cylinder walls, honed and running the cleaned factory pistons and old rings, one step further would be pistons as strong or stronger than factory with 7.4:1 compression ratio. That's as durable as the engine can get but tuning is everything, there are engines that even with the best tune the engines weak point will fail, this isn't one of them. The biggest engine bore you could manage would be 0.050" = 1.27mm, 1.27mm to an 86mm piston is a 0.0147% increase in size, that's almost a 3% increase in displacement but what % of the cylinder sleeve is getting removed, it's probably less then 1/4" but 1/4" is 6.35mm and a 1.27mm bore is 20% or 1/5th of the strength removed, just for perspective 0.0147% in fraction is 147/1000000th.

These engines aren't much at atmosphere, they aren't bad for what they are but they are far from N/A tuned marvels, you can run all the N/A tuned bells and whistles in the world a 3 angle vale job, profiled cam, 12:1 compression ratio, 0decked block, knife edged crank... and any 2.0l 16 valve engine holds more potential. But what the F2T is, an under engineered over build engine with enough air flow to spool large turbos with low enough compression and strong enough to pump massive volumes of forced air. An engine is just an air pump and the f2 isn't much of a pump but under boost the turbo becomes the pump and the engine is just a restriction between the air and exhaust, the F2T is a low restriction engine for boost.

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post #3 of 8 (permalink) Old 4-20-17, 19:45 Thread Starter
 
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Originally Posted by Mazda Carnage View Post
Well I sent you an email, you can post it here to get opinions on my thoughts.

When you say " i really dont plan on beefing it up" what exactly do you mean? the only thing you can do is buy rods with studs which aren't a weak point or needed until making insane engine pressure and record F2T power. Knife edging the crank, boring the block, running wiseco 8.5:1 pistons all weaken the engine.
To me the "beefiest" F2T possible is bone stock with lightly warn cylinder walls, honed and running the cleaned factory pistons and old rings, one step further would be pistons as strong or stronger than factory with 7.4:1 compression ratio. That's as durable as the engine can get but tuning is everything, there are engines that even with the best tune the engines weak point will fail, this isn't one of them. The biggest engine bore you could manage would be 0.050" = 1.27mm, 1.27mm to an 86mm piston is a 0.0147% increase in size, that's almost a 3% increase in displacement but what % of the cylinder sleeve is getting removed, it's probably less then 1/4" but 1/4" is 6.35mm and a 1.27mm bore is 20% or 1/5th of the strength removed, just for perspective 0.0147% in fraction is 147/1000000th.

These engines aren't much at atmosphere, they aren't bad for what they are but they are far from N/A tuned marvels, you can run all the N/A tuned bells and whistles in the world a 3 angle vale job, profiled cam, 12:1 compression ratio, 0decked block, knife edged crank... and any 2.0l 16 valve engine holds more potential. But what the F2T is, an under engineered over build engine with enough air flow to spool large turbos with low enough compression and strong enough to pump massive volumes of forced air. An engine is just an air pump and the f2 isn't much of a pump but under boost the turbo becomes the pump and the engine is just a restriction between the air and exhaust, the F2T is a low restriction engine for boost.
Thanks again carnage. I really think I'm just going to yank it out and send it to a reputable machinist. I know a guy in the area and actually spoke to him about it today and the price he gave me wasent all that bad. He did get me a little nervous telling me i may need a crank. I guess I'm gonna have to get the engine out and see....

Btw when I said I dident want to beef it up I ment I have no plans on building the car to go fast.
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post #4 of 8 (permalink) Old 4-20-17, 19:53 Thread Starter
 
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Originally Posted by Mazda Carnage View Post
Well I sent you an email, you can post it here to get opinions on my thoughts.

MAZDA CARNAGE'S EMAIL...

...Don't know about the torque converter walking the crank. Crank walk is usually a manual transmission problem mostly caused by heavy duty pressure plates and dropping the clutch too slowly under high revs. The fingers/splines or whatever they are called have a tipping point effect on the pressure plate surface usually they start moving whith the pressure plate still engaged (this is when they are the most stiff) once the plate starts to move off the disk the get easier to move (release the clamiping force that locks the disk), so when launching you can have the clutch engauged but still be applying pressure on the pressure plate fingers, these fingers apply the clamiping force of the plate to the disk and so now the clamping force (350 to 500 ft lb torque) is applied crank thats made of rough finish cast iron and is spinning at high rpm onto/against the thrust bearing and the coated copper bearing looses to the crank everytime.
If the pressure plate is unsprung then there is no tipping point and the pressure is always on the main thrust bearing when pressing the pedal.
If your rocker HLA's aren't collapsing from bearing dust then there is a good chance you havent damaged the crank main or rod journals. It's the brearing metal floating in the oil that damages things not the actual, gradual walking of the crank. But the longer you wait the greater the chance of ruining the crank and killing the rod bearings wich ovals the rods and caps, seizes the wrist pins and chews up the cylinder walls and finally chews the cam jounals caps and head. The caps and head can be machined and have bearings installed to run the cam but....

Learn your clutch pedal, if you have to ride it in traffic or when launching learn how (while idling, realese the pedal slowly and find the point the idling engine moves you without stalling, thats the bottom of the engagement point, then learn the middle and always release the pedal above that), learn your clutch and you will be able to abuse it properly and still have it last longer. Lear your clutch and tame your crank:


-You can get the crank out without pulling the engine but the transmission has to come off and the oil pump and he rear main housing and it's a pain in the ass....
-I do have spare cranks.
-Personally I would buy a set of main bearings and rod bearings (in advance or wait t'ill you inspect the crank), 1gallon of the cheapest 10w40 motor oil, 1 gallon of Castrol GTX 20w50, 1 oil filter, a felpro oil pump gasket set (contains pickup gasket, crank seal and oil pump Oring 8-10$), 1 tube of high temp gasket maker or RVT ... Locktite red
-Drop the oil.
-Remove the passenger link kit, undo the sub frame at the front and frame rail and swing it under the floor (while it hangs from the ball joint).
-Pull the transmission dust shield (5x 10mm M6's).
-Remove the small front transmission bracket (under the turbo).
-Pull the 19 oil pan bolts
-Pull the oil pick up and windage tray.
(30minutes to 1hour)

-Pull the rod caps one at a time, inspect the bearing and crank and retorque them (the rod bearings will alway wear, damage/ go faster then the crank mains) If the rod journals look shiny and smooth then the crank mains should be fine.
Label all 5 main bearing caps and remove them, look for damage, grooving or wear on the crank lobes (90% of the time it should be fine).

[(If they aren't fine, pull the crank and have it turned/milled .025" undersize and buy .025" overised bearings bearings. (bearings are the same price, turning costs about the same as shipping a crank would and hive a new finish to the crank))].

The crank will be hanging by the rear main seal and oil seal and you can pull the upper bearing halves out. Take a roofing nail (the kind with the thin flat heads), cut the nail down to 1", you put the nail in the oil passage of the main bearing journals and use it to push out the bearings, the center thrust bearing (the one that holds the engine in place) push on the edge with a flat screw driver and turn the crank to get it out.
** Draw a diagram, take a picture or a video of wich way the upper bearing sits so the oil hole lines up on the block, pay close attention to where the little tab is on the bearings so you don't put the bearings in backward (yes it can be done).
Use brake cleanrer to spray and clean where the thrust bearing was and anywhere you see shiny or copper dust.
Cover both sides of the bearings in assembly lube, but them against the crank and turn the crank while holding the bearing (making sure it's sliding in between the crank and block) and turn the crank until it's in place.
Torque them the correct amout in the proper order.
(1 - 2 hours)

The longest part of bottom end work is cleaning all the old gasket maker off the tray pan and block, I find the best tool to remove the old gasket is a "3/4" plastic handled wire brush for copper pipe" (Google "") looks like this:



Apply Gasket maker to the top side of the tray and instal it (use locktite on the 2 mounting bolts) instal the oil pick up (locktite all 3 bolts). (You don't want 10mm m6 bolts wiggling loose and floating around in the engine).
If you left the exhaust on the car, apply gasket maker most of the way around the oil pan (not where it sits against the rear main seal housing), apply gasket maker to the bottom of the windage tray in that spot (make sure your pan bead and tray bead meet or overlap a bit) and instal the oil pant.
*** Remeber the 2rear main pan bolts and the 3 oil pump pan bolts (and 2 oil pickup bolst) all screw in to aluminum that can strip easily, tighten them carefully.

NEXT---

Oil pump crank seal, pull the pulley and timing pulley, take a drywall screw like this :

screw it into the crank seal, then you can A) use it to pull out the seal, B) remove it, grind the tip smooth and screw it back in, keep screwing, once it reaches the oil pump it pulls out the old seal.

-Oil the new seal and slide it into place, place the old seal over it (flat side against the new seal face), take a piece of pipe and put it over the crank against the old seal and tap in the new seal.

-When reinstalling the timing belt with the utility pulley lined up with the TDC mark, move it back 1 degree, this will make it easy to slide over the cam pulley, then turn the crank and the 1 degree slack will move to the tensioner side, timing will be dead on and you wont have to fight with the belt.

-REMOVE THE RATCHET AND 21MM FROM THE CRANK BOLT.
-Put the cheap 10w40 oil in the engine and run the car 5 to 10 minutes (you should still be running the old oil filter thats on the car now), dump the oil and install the new filter and 20w50 motor oil and you are done.

.
Thanks for taking the time I really appreciate it

Last edited by Somedoode; 4-22-17 at 7:29.
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post #5 of 8 (permalink) Old Yesterday, 11:17
 
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Originally Posted by Somedoode View Post
Thanks again carnage. I really think I'm just going to yank it out and send it to a reputable machinist. I know a guy in the area and actually spoke to him about it today and the price he gave me wasent all that bad. He did get me a little nervous telling me i may need a crank. I guess I'm gonna have to get the engine out and see....

Btw when I said I dident want to beef it up I ment I have no plans on building the car to go fast.
I don't think the crank will be as bad as you think it will. Autozone sells a reman crank for about 200$ if you really need one, comes with main and rod bearings, but you can run different ones as long as you buy the right size, oversize bearings and pistons usually have their size stamped on them.

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post #6 of 8 (permalink) Old Yesterday, 19:08 Thread Starter
 
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Quote:
Originally Posted by Somedoode View Post
Thanks again carnage. I really think I'm just going to yank it out and send it to a reputable machinist. I know a guy in the area and actually spoke to him about it today and the price he gave me wasent all that bad. He did get me a little nervous telling me i may need a crank. I guess I'm gonna have to get the engine out and see....

Btw when I said I dident want to beef it up I ment I have no plans on building the car to go fast.
I don't think the crank will be as bad as you think it will. Autozone sells a reman crank for about 200$ if you really need one, comes with main and rod bearings, but you can run different ones as long as you buy the right size, oversize bearings and pistons usually have their size stamped on them.
I think you are absolutely right! After talking to a few people and carefully reading your write up you kind of gave me the courage to go at iya on the car. I'm going to do pretty much what you suggested.

I have a set of standard main and rod bearings coming tomorrow...this Saturday I plan on jacking the car up and taking one main cap off at a time (going straight for that middle thrust bearing. going to inspect the crank journals and the bearing and replace and tourqe down and to the next one.

I don't think I'm going to even mess with the rods at all? What do you think? the car wasn't knocking...?
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post #7 of 8 (permalink) Old Yesterday, 22:13
 
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Like Mazda Carnage said earlier, if any bearing are going to wear out first it'll be the rod bearings not the mains so I personally, from experience, would pull the ROD bearings and at minimum inspect them. Since you're already there replace them if you already have new ones, piece of mind you know. At that point you might as well do the mains, it's all apart and it'll be the same amount of work reassembling everything either way so I'd make it worth the effort.

As far as the marks on the timing cover, you don't know that that car hasn't broke an alternator belt, ran over road debris, had the alternator belt put on wrong, a stick, rock, debris, squirrel fodder, etc., get in between the balacncer and the cover, the car is 29 years old, the possibilities are endless. And the seal leaking, once again, the car is 29 years old with only 86,000 on it. It has sat a lot and that is harder on seals than just about anything. Add boost pressure to that and your going to find leaks reals quick.

Just my 2.5 cents.

91' MX6 DX with 91' GT ECU and bits - Garret TBO-335, SCG-1, 2.5" exhaust, no cat, etc. Bosch 4-hole injectors, Probinator, AEM X-series Wideband, AEM water Methanol Injection, 17" MB Alpina Black Wheels, 215/45 GT Road Hugger Ultra- Coming soon - MS2-DIYPNP already built, Ford EIDS

Last edited by tazman171; Yesterday at 22:30.
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post #8 of 8 (permalink) Old Today, 11:01 Thread Starter
 
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Originally Posted by tazman171 View Post
Like Mazda Carnage said earlier, if any bearing are going to wear out first it'll be the rod bearings not the mains so I personally, from experience, would pull the ROD bearings and at minimum inspect them. Since you're already there replace them if you already have new ones, piece of mind you know. At that point you might as well do the mains, it's all apart and it'll be the same amount of work reassembling everything either way so I'd make it worth the effort.

As far as the marks on the timing cover, you don't know that that car hasn't broke an alternator belt, ran over road debris, had the alternator belt put on wrong, a stick, rock, debris, squirrel fodder, etc., get in between the balacncer and the cover, the car is 29 years old, the possibilities are endless. And the seal leaking, once again, the car is 29 years old with only 86,000 on it. It has sat a lot and that is harder on seals than just about anything. Add boost pressure to that and your going to find leaks reals quick.

Just my 2.5 cents.
Good advice thank you. I will pull the rod bearing as well. Wouldn't want to pull that pan again that's for sure.

One question about the oil pan. I notice they do show a cork gasket available but in the wsm it seems they just use rtv. You guys have good luck just sealing them with rtv only?
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