Mazda MX-6 Forum banner
41 - 60 of 84 Posts

· Registered
Joined
·
41 Posts
Discussion Starter · #41 ·
Sorry for not posting for a while, things are happening but only very slowly.
Managed to get the sump off the old broken engine, got a piston out and got a ring off it to replace the broken one on the new engine.
So all pistons are back in the block now.
Also cleaned out all the loose matter from the coolant passages etc.

Main hurdle at the moment is trying to find a part number for the splash plate gasket (or what the Mazda workshop manual calls the "stiffener") - i.e. between it and the block.
The Felpro kit I ordered only contained the gasket for between that and the sump (oil pan) itself and after lots of searching I can't find anything online.
Should I just use sealant without a gasket? Seems to be what the workshop manual suggests

Font Parallel Rectangle Paper Paper product


Also - @Mazda Carnage regarding your tip about torqueing the oil pickup in advance to "pre crush" the gasket etc - I went to do this but it's just a paper gasket, so I can't see the point? It only makes sense to me if it was a rubber gasket.

One other question - this may have been my fault from removing the sump, but there is a gouge in the material of the block near where the oil pickup bolts on. I got rid of any small loose pieces of metal, but is this likely to be an issue?

Wood Gas Metal Circle Auto part


And just thought I'd drop a pic of where it's currently at:
Vehicle registration plate Motor vehicle Hood Automotive tire Automotive design


As an aside - I have now ended up with another 626 parts car which could be handy - my mechanic had a customer who wanted to get rid of it and knowing I had this project, he put me onto him and I bought it very cheaply. I gave it to a family member who was in need of a car and it did a solid 5000km or so of driving before overheating.
Thinking it may be the head gasket I did a compression test and all cylinders were around 120psi, except #1 which was a few psi less. However, while I was testing # 2/3/4, a bit of coolant spat out the #1 spark plug hole - is there any way this is anything but the head gasket?
If it is the head gasket, I'll just turn it into a parts car.
 

· Registered
Joined
·
3,015 Posts
Mazda uses gasket maker. Companies sell cork oil pan gaskets for these cars but using them make stripping the oil pan bolts possible before achieving torque due to the gasket thickness. Use a tiny continuous bead in the same place the manual states.

Also - @Mazda Carnage regarding your tip about torqueing the oil pickup in advance to "pre crush" the gasket etc - I went to do this but it's just a paper gasket, so I can't see the point? It only makes sense to me if it was a rubber gasket.
I have torqued the oil pickup to speck during assembly (after the "stiffener" before the "oil pan") to proper spec with high temp threadlock on the M6 bolts only to have the gasket crush over time (don't know how long it to) and leave just enough slack on the oil pick up bolts to have them loosen up over several months cause the engine to loose oil pressure and spinning the rod bearings. So now I pre-seat the oil pick up gasket to prevent that from ever happening again.
This happened only once in more than 30 installs but that was still once to many times.
Because the oil pump is aluminum adding torque to the oil pickup bolts isn't a good idea.

As an aside - I have now ended up with another 626 parts car which could be handy - my mechanic had a customer who wanted to get rid of it and knowing I had this project, he put me onto him and I bought it very cheaply. I gave it to a family member who was in need of a car and it did a solid 5000km or so of driving before overheating.
Thinking it may be the head gasket I did a compression test and all cylinders were around 120psi, except #1 which was a few psi less. However, while I was testing # 2/3/4, a bit of coolant spat out the #1 spark plug hole - is there any way this is anything but the head gasket?
If it is the head gasket, I'll just turn it into a parts car.
Could be a leaking intake manifold gasket but that wouldn't cause overheating.
It's an N/A motor, they don't overheat the way a turbo motor does, just throw on a head gasket and drive it. the job can be done in 3 hours without having to remove the harness connectors, remove the intake to block bracket, drain the coolant, undo the EGR pipe at the exhaust manifold, unbolt the exhaust manifold and pull it from the head, set the timing and remove the belt from the cam gear. remove the rad hose at the Tstat, disconnect the oil pressure switch, the throttle body coolant hose, the rear housing coolant hose, the head bolts and lift the head about 1 foot above the block. put cardboard over the block and clean the head's gasket surface, remove the cardboard and clean the block surface.
Install the new head gasket and reassemble.
 

· Registered
Joined
·
41 Posts
Discussion Starter · #43 ·
Mazda uses gasket maker. Companies sell cork oil pan gaskets for these cars but using them make stripping the oil pan bolts possible before achieving torque due to the gasket thickness. Use a tiny continuous bead in the same place the manual states.
The Felpro kit I ordered included a cork gasket for the oil pan itself but no gasket for the splash plate/stiffener. Are you saying to use sealant for both and not use the cork gasket at all?

Could be a leaking intake manifold gasket but that wouldn't cause overheating.
It's an N/A motor, they don't overheat the way a turbo motor does, just throw on a head gasket and drive it. the job can be done in 3 hours
That may be the case but if the head has warped at all that's an extra few hundred $ to get a shop to machine it.
If the car was in good cosmetic condition I'd do it, but not sure it's worth it given it's a bit rough.
 

· Registered
Joined
·
3,015 Posts
The Felpro kit I ordered included a cork gasket for the oil pan itself but no gasket for the splash plate/stiffener. Are you saying to use sealant for both and not use the cork gasket at all?
Yes.
 

· Registered
Joined
·
41 Posts
Discussion Starter · #45 ·
Got the sump on today
Motor vehicle Hood Automotive tire Bumper Automotive exterior


Couple of questions -
1. Just wanted to confirm that the oil pickup was just meant to have a gasket, not an o-ring as well?
2. Are the F2 and F2T distributors the same? It's missing from the turbo motor but I still have the old NA one.
3. Showing my lack of knowledge here but is it normal for the valves for one cylinder to be slightly open and all the others closed? (see pic)
Automotive engine gasket Auto part Motor vehicle Metal Fashion accessory
 

· Registered
Joined
·
3,015 Posts
1- Just the gasket at the pickup, no Oring.
2- N/A has vacuum advance distributor, gt has computer generated timing.
3- yes valves will always be opened no matter where the cam is turned to. 2 IN ,1EX
 

· Registered
Joined
·
41 Posts
Discussion Starter · #47 ·
So because the plan was to use the old NA ECU and wiring harness, should I reuse the NA distributor too, or will I still need to find a turbo one?
Just not sure about how a turbo one will work if it has computer controlled timing but I'm using an NA ECU
 

· Registered
Joined
·
41 Posts
Discussion Starter · #48 ·
@Mazda Carnage I tried your tip of putting spark plugs in the head, backing the rockers off and filling the combustion chambers with degreaser.
Worked great! On 3 of the 4 that is - on the other one it kept draining out as one of the valves was still open very very slightly.
Does this point to a more serious problem?

Next step is to do some work on the head, including valve stem seals. No idea what I'm doing but the workshop manual seems to have pretty clear steps for this.
 

· Registered
Joined
·
3,015 Posts
@Mazda Carnage I tried your tip of putting spark plugs in the head, backing the rockers off and filling the combustion chambers with degreaser.
Worked great! On 3 of the 4 that is - on the other one it kept draining out as one of the valves was still open very very slightly.
Does this point to a more serious problem?
Make sure the rockers are backed far enough on that combustion chambers valves, if it is and the valve still leaks, when you do the valve stem seals LAP the valves.
Buy some medium valve grinding compound. (grey gritty paste, +- 10$), find fuel hose that fit's over the valve stem (1/4" or 5/16"), you need a 2" long piece (5cm), two small hose clamps, a 1.5" long round bar that fits in the fuel hose and a drill with reverse.
Also if you can get some valve spring shims:
Valve sping shims..
1$-2$ each.

I recommend following these steps:
1- Install the valve spring compressor on the valve and compress the spring.
2- Wrap a socket in a rag and put it under the calve (in the combustion chamber).
3- Grab the spring compressor arms with one hand, hold the arms against the valve and create a pocket with your hand to prevent the valve keepers from flying away, tap the top of the valve spring compressor with a hammer until the upper spring cap and keepers separate, use a magnet to grab the keepers.
4- Set the spring compressor aside with the spring in it and remove the thing metal seat that sits under the seats. Remove the valve (clean in in you want), apply grinding compound to the seat face of the valve and put the valve back in the head.
5- Put the hose over the metal bar (1.5") and clamp the hose, install the bar in the drill, put the other end of the hose on the valve and clamp it down. Hold a rag against the valve with on hand and the drill in the other.
6- Sin the drill slowly while applying pressure on the valve with the rag, as the valve spins apply and release pressure on the valve with the rag (just open -pressure close) after 10 seconds switch the drill direction and do the same thing in reverse for 10 seconds, 4 to 6 ten second cycles per valve (keep the numbers even forward/backwards.
7- Remove the valve from the head and clean it with a rag, also clean the valve seat off. You can use varsol, thiner, alcohol... to get all the grinding compound off.
8- Grab the valve stem seal with a pare or locking pliers just tight enough to grip it, spin the seal on the stem and pull or tap it off with a hammer.
9- Oil the top of the valve stem sleeve, oil the new valve seal rubber, put the valve in the head, if there is an clear plastic install sleeve, put it on the valve stem and slide the seal over the valve stem and line it up with the sleeve, put the old valve stem seal against the new seal and tap it with a hammer until the new seal is seated on the sleeve. Remove the clear install sleeve from the valve (the install sleeve isn't necessary to swap valve seals).
10- Put the metal spring seat on the head, install the spring spacer, put the spring and compressor back over the valve and put the valve keepers back in place, pull up on the spring compressor to hold the keepers in place and unscrew the spring compressor and remove it.
11- Aline the valve spring on the metal seat and shim.
12- Repeat process to the 11 other valves.

This process keeps you from mixing valves up, mixing springs or keepers (intake and exhaust are different) or putting valve springs on upside down.
Lapping (grinding) adds a couple minutes to each valve seal install. If you have a nice cut surface on the valve and seat it will seal, with 0.06" shims the spring will have more force than it did new.
I like to place all the springs in the same position (coil start and end) on each side of the head, this isn't necessary but I insanely imagine it gives all the springs and valves the best chance of performing the same.

If you clean the valve ports as well you will have completely restored original factory performance from the engine, reliability and longevity also, it will be like a brand new motor that is broken in.
If you remove any material from the head ports it will be a performance increase over factory.

Tug on each valve seal after installation, if they go on at the slightest angle they will stretch and will float with the valve yielding very low compression on that cylinder. If you can pull the seal off with your hand, you must carefully crush it a bit and reinstall it, if you can still pull it off you must replace it.
 

· Registered
Joined
·
3,015 Posts
If you don't have a drill you can do them manually with a suction cup valve lapper, they cost 10$ or less, should cost you 20$ or less to re seat the valve like new.
 

· Registered
Joined
·
41 Posts
Discussion Starter · #51 ·
Thanks, I think most of that makes sense, just a couple things I wanted to check.

What is the advantage of the valve spring shims? I was hoping to get to work on this in the next few days and I don't think anything I order will arrive before then.

In the steps you listed, can you clarify #11. The valve will already be in place in the head after #10 so I'm not sure what lining up you mean.

Also just to make sure I've understood correctly - basically the only special tool I need is a valve spring compressor (and suction valve lapper if I choose that method), ie normal pliers and hammer are enough to remove and install the seal without using a specialist tool?
 

· Registered
Joined
·
3,015 Posts
Valve springs loose tension over time, they are heat cycled and compressed millions of times.
The factory specs are.
Freestanding length:
Intake: Standard- 49.5mm Minimum 48.3mm
Exhaust: Standard- 50.4mm Minimum 49.2mm

By adding 1.524mm spring shims, valve spring seating pressure is restored to factory (or greater). This assures that the valves will seal when shut and reduces valve float.

-----------------
Step 11 edited.

-----------------

Yes but locking pliers work best, with normal pliers pressure must be applied and when the valve seals comes off the valve sleeve it will crush under normal pliers pressure.
 

· Registered
Joined
·
41 Posts
Discussion Starter · #53 ·
Had a fairly productive weekend.
-Changed valve stem seals
-Lapped the valves
-Resurfaced the head
-Reassembled head with cam, rockers etc
-New camshaft seal & gasket (timing side)
-Installed head gasket & head
-Valve cover

How it sits currently:



However theres one thing I'm a bit concernd about, after we did all that I realised the Mazda workshop manual says to put sealant on the head before installing the camshaft caps on the far left and right (see below), which I didn't do. Do you think this will be an issue? It's basically just metal on metal so I can understand why there should be sealant there.

Rectangle Font Parallel Pattern Paper product


Also, I didn't take a photo but I noticed that on the thermostat and distributor side, the camshshaft is actually different. I think I'll be using the NA distributor since I'm using the NA wiring harness etc so should I have used the NA camshaft too?
 

· Registered
Joined
·
3,015 Posts
Without sealant on the cam caps oil will mix with coolant in the front and rear housings.
The 88-89 cams have an extra lobe near the distributor for a hydraulic fuel pump but all F2 cams are the same lift and duration and are completely interchangeable so use the cam that looks the least worn.
 

· Registered
Joined
·
41 Posts
Discussion Starter · #57 ·
Got a bit done on the weekend again.
  • Fixed my previous mistake by adding sealant under end cam caps
  • Installed thermostat housing, new thermostat, etc
  • Removed old engine from the car, separated gearbox
  • Removed alternator from old engine and installed on the new one
  • Swapped the AC compressor and power steering pump from the old engine to the new one as they were known working. Also turned out the PS fittings were different.
  • Removed crankshaft bolt from old block with great difficulty and installed in new engine
  • Installed all timing gear, timing belt, timing cover



2 questions:

1. In your experience is it easier to fit the intake manifold before or after putting the engine in the car? I was thinking it would be easier to do it with the engine out of the car but it might make it harder to fit the engine in, plus having it off might make some of the wiring etc easier.

2. just wanted to double check I did everything right so that the timing will be correct as I've never done a timing belt before let alone after having the head off
  • When installing the cam, made sure the dowel was facing up
  • Made sure the #1 was facing up when installing the cam gear; it also lined up with the mark on the housing on the side of the head
  • Turned the crankshaft pulley so the mark at the top lined up
  • After installing the timing belt, turned the engine over a few times by hand to make sure the valves weren't hitting anything

Also this is a photo of the engine with the crank pulley lined up, just to make sure it's correct
 

· Registered
Joined
·
3,015 Posts
Your pictures aren't working.

Answer 1
It is much easier to put the intake on before installing the motor, there is plenty of room to lower it in, should be even easier with the N/A gearbox. Most of the engine harness connects to the intake anyway.

Answer 2
Timing Belt:
Align the arrow at 1 on the cam gear with the arrow on the front head housing.
Align the crank gear divot with the mark above it, then turn the crank back 1mm (counter clockwise).
Install the timing belt and reattach the tensioner spring, turn the crank clockwise 2 full rotations until the cam arrows align again, check the crank mark alignment and tighten the tensioner bolt.

The 1mm counterclockwise movement on the crank before installation puts enough slack on the "front" of the timing belt to slide it over the cam gear and get it in the right position. When the crank is turned clockwise the slack is moved to the "back" of the timing belt (tensioner) before the cam gear will start to move.
 

· Registered
Joined
·
41 Posts
Discussion Starter · #59 ·
Not sure what's wrong with the photos, they show up on my end, were you able to see photos in my previous posts?

I understand what you're saying about the timing belt. When I did it I didn't turn the crank back 1mm however after turning the crank 2 rotations the marks align perfectly so I think it's fine.

Next thing I need to work out is the wiring.
The challenge I have is that the engine is 1989 (A spec) and the car is post 1990 (B spec). There is a guy selling both versions of the turbo ECU so I have different options available but I'm not sure which will be best. I think the options are:

1. Run the original NA ECU and wiring and adapt to suit the F2T
2. Run an A spec F2T ECU and adapt/splice to suit the car's wiring (eg where dash wiring plugs into ECU etc)
3. Run a B spec F2T ECU and adapt/splice to suit the engine's wiring.
4. Run a standalone engine management system (eg Haltech)

The problems I see with each are:
1. I'm not convinced the NA wiring will match up to everything properly - presumably there will be at least a few sensors etc in the F2T that are different. There will also be less potential of tuning or running more boost etc later.
2. No idea if it's actually possible to do this - I'd need to somehow find wiring diagrams etc
3. Would require a lot of new sensors, and different injectors, etc
4. Cost - this is a last resort option as it would probably require as much money as I've spent on the whole project so far.

What is likely to be the most effective option, and the option least likely to give problems?
 

· Registered
Joined
·
3,015 Posts
All your photo's show up except the last 4 you've posted.

Funny story, this guy (was a member here), sold me a 1989 mx6 GT, he dropped in a 1990+ F2T, him and his friends hacked up the engine harness trying to get it to wire to the Bspec F2T, they destroyed the harness and he was selling the car. I asked him why he didn't just swap the distributor and intake manifold ?
Now I remember which car the [email protected] up wire harnesses I pulled out last summer come from.

The answers to the options you posted:

1- Put the N/A intake and rear housing/distributor on the GT head, plug in the N/A harness. If you want the turbo logo than swap the injectors, or dynamic chambers or whatever. throttle sensors are the same, just different vacuum ports.
The 2.2l N/A runs vacuum advance distributor ignition timing, google how to modify vacuum advance distributor for boost and how to lock it out, mechanical timing is much easier to alter than factory electronic ignition. You just need a digital timing light to set the lockout at 20* or 22* or whatever total advance you want.
Fuel, you can set up an injector emulator (look it up) that runs off a pressure switch to 1 extra injector on the charge pipe before the throttle body.
How much fuel is needed shouldn't be too hard to ballpark.

N/A injectors are rated to flow 176-244 cc/min (that's a huge variance), average 210cc
GT injectors are rated to flow 292-360 cc/min, average 326cc

F2 injectors are batch fired 2x2 so in 1 minute the maximum fuel CC the 4 injectors can deliver at 100% duty cycle is 410cc for N/A and 652cc for GT.

We know there is a safety window, the N/A injectors never run close to 100% duty cycle and GT injectors can handle 16psi on a bone stock motor and turbo (in your case probably 15psi because of the climate, fuel cools the air).

We know the GT boosts 7-8psi factory. We know the safety window on the injectors is enough to boost another 7-8psi before running out of fuel.

We know that air full ratio's are different for WOT n/a and forced induction 13.0:1 N/A 11.8:1 GT
at 7-8 psi (lets say 7.5psi) 1/2 bar the engine is getting 1.5 bars of air, it's consuming atmospheric pressure (1bar) with 100% volumetric efficiency + 1/2 bar/7.5 psi above atmosphere.
At 15psi boost that's 2bars/ 29.4-30psi of air going into the engine.
30psi air on a stock F2T engine requires 652CC/min of fuel.
There is about a 10% air /fuel ratio increase requirement under boost.
652 x 10% = 65.2
F2T Fuel requirements above atmosphere:
652 / 2 = 326 + 65.2 = 391.2 CC @ 15psi boost
391.2cc / 2 = 195.6 CC of fuel @ 7.5psi boost

F2 n/a fuel requirement at wot
652 - 65.2 / 2 = 293.4cc
or
652 / 2 = 326 - 10% = 293.4cc

N/A requirements - N/A injector rating
410cc - 293cc = 117cc fuel should come from the injectors when the airflow meter flap opens past n/a engine flow.

195.6CC of fuel required for 7psi boost , N/A injectors should deliver half that .

A single injector pulsed of 1 batch fired injector will deliver half it's rated cc/min at X duty cycle . which would be 200CC

The extra injector delivery should be calculated at 85% of it's duty cycle (safety window).
so one 230CC injector should get you 7psi
The next 7 psi would require : 195.6 say 200cc X2 + 15% = 460cc extra injector piggy backing off one of the factory injectors from the 2nd bank .
But a set of GT injectors pulsing off each injector bank would deliver 326cc vs the 230 and 460cc delivering 345cc

How it works is you set the normally closed pressure switch to 2.5 or 3psi and run the ground signal from the homemade piggy back signal emulator through it, above 3psi the extra injector pulses at the duty cycle of the injector that's being emulated.

You just need a wideband, a proper functioning boost controller and to make sure your fuel pressure regulator is getting a boost and vacuum signal.

Options 2 and 3 are very similar, both will require the igniter and coil and connections added to the harness that goes to the firewall fuses, require adding wires to the engine harness, a factory ecu connector or a lot of splicing and changing harness connector on the distributor, splicing wires...

Option 4, look up speeduino or lock you N/A distributors timing and get an extra injector controller. Same fuel pump and it can handle 15spi.

Problems:
1 only the knock sensor wont connect to the harness if you follow my instructions for 1.
2 you need the wiring diagrams + see option 2 and 3.
3 see problem 2.
4 speeduino is a lot of work and learning turner studio but not expensive, extra injector controllers are easy to install work very well and don't cost a lot. No matter what you need a wideband and boost control. You can run different rate or adjustable rate FMU in place or the fuel pressure regulator and dial in 7psi boost on the factory N/A injectors with higher fuel pressure and a wideband.

And keep looking for someone parting or selling a F2T car after they blew the motor and can't or don't want to find a replacement. If you find one go look at and say what "you really wanted was the motor, it's kind of worthless without it, so how much do you want for the rest".
 
41 - 60 of 84 Posts
Top