7MGE Engine rebuild

[oregonjoe]

Block was $200 to shave and dip tank, check for cracks. The total Machine shop bill was $750 wich was head job, block and crank, and alot of cleaning (all intank manifolds and oil pan) I bit high but around here I am luck to get anyone who can work an import engine.

[oregonjoe]

After a week in the machine shop – finally got my block back.



Tests showed no cracks so that’s good. The head gasket had been leaking water for some time so there was a lot of pitting around the water ports. The shop had to plane the block surface to remove most of the defects and prepare for the new gasket.



Cylinders only needed a hone to bring them back into shape.



While it was in the shop – I cleaned up the pistons and timing cover parts. The Crank Shaft just needed a little polish to restore as new so now I’m ready to start the rebuild on the block.



Ran into a problem with the oil pump drive shaft. There are two bearings in the block for the shaft that were left in when the block was tanked which of course destroyed the bearings. The problem is that they are really almost impossible to replace with the crank and pistons in place so now I have to wait till Monday to get new bearings before I can proceed. In the meantime I will check the oil clearance on the crank and rods with plastigauge.

O well, lesson learned – remove everything from the block and be sure you have all the bearings before reassembly.

[oregonjoe]

Assembled the crank and pistons into block. Laid the crank in on the new dry bearings and placed a piece of plasticgauge on the bearing face.



Torque the main caps to crush the gauge and then removed the caps. Check tolerance was OK (0.022) then cleaned and reassembled again.



Takes awhile to do it twice but felt better to know everything was in spec after 20 years. After the crank was bolted in the second time, it spun with very little effort – smooth as silk with all that assembly lube.

Next it was the pistons. Cleaned till new and disassembled and cleaned the writ pins. Reassembled the rods to pistons being sure all the little oil holes in the pistons were clean. Placed the rings on the pistons after checking ring end gap in cylinder bores. Amazed how much easier the rings go on then come off. After they are in the engine for awhile they get very brittle and just break. Performed same plasticgauge check on rod bearings as crank. Assembled pistons into ring compressor and pushed into cylinder from below (block was inverted on engine stand). Used some old fuel line tubing over the rod bolts which works really well because if you cut them about 3” long, they actually guide the rod onto the crank. All the pistons tapped in very easy.



After pistons were installed with no problems, tried to give crank a spin and found it wasn’t easy. Using a torque wrench, I had to set it to 15 pounds to break the inertia and get the crank to move. Not nearly the same as when the engine was broken in. I know its going to take some time for the pistons to seat and for things to loosen up but wonder if 15 pounds is spec. I just think about all those new engines rolling off the production lines everyday with just a few hours of break in time. A lot of extra gas being wasted in the first 500 miles.

I cleaned the oil pump till it looked like new and gave it a test in a bucket of oil. Inserted the oil pump drive shaft and pressed in the pump.



Still waiting for head and clutch to arrive so all I can do now is clean parts. The biggest cleaning job is the intake manifolds as they are clogged with residue from the smog stuff. PVC and EGT just destroy all the air passages. The throttle body took 2 days to soak off the layer of tar. Sure will be nice to get this engine to breathe again.

[oregonjoe]

Picked up clutch. $200 for pressure plate, disk, throw out bearing, pilot bearing, and alignment tool. Had the old flywheel resurfaced by the shop.



Forgot to pull out old pilot bearing on the crank before the shop work was done so I had to pull it myself but did not have a tool. Remembered an old technique for years past – packed the pilot hole with grease and used a 3/8” socket extension and hammered into hole. The hydraulic pressure of the grease from behind pushed out the bearing. Took 4 hits with grease repack but it came out pretty smooth. Put new bearing in with a ?” socket just tapping on the edge of the bearing.



Mounted the new clutch and aligned the disk with the tool. The book says to torque the clutch pressure plate to 15 pounds but that seemed kind of low. I thread sealed the flywheel and clutch bolts anyway.

Now it was time to chain up the block and lift it back into the car. I am dong the block with out the head because it’s easier to move around and get in a do the bell housing bolts without the head on. I was concerned about alignment with the transmission shaft as it seemed real easy to snap it off if things were not aligned right when lifting the block back in.



Now – a few things I learned. First, put the two top bell housing bolts in before doing anything. I found it impossible to get them in after the transmission was jacked up to the firewall which you need to do to get the right angle to join with the block. Second, jack up the transmission all the way to the firewall to get a better angle. When you lift the block in, the front of the engine is about 30 degrees up from the rear so the oil pan can clear the lower support beams. Here is the important part – unbolt the clutch slave cylinder from the bell housing so the clutch fork is able to completely retract. It took me almost 2 hours in trying to match the block and transmission and not getting them together until I realized the clutch fork/throwout bearing was trying to engage the pressure plate that no mere human can push against. Disconnecting the slave cylinder allowed the clutch to slide in over the shaft with no pressure – SIMPLE.



When I removed the engine, I unbolted the two support mounts from the block and not the frame – it was just easier due the angle of the frame bolts. On reassembly I bolted the transmission on before attaching the engine mounts – bad idea. It is impossible to put the mounts back on after the engine is set in unless you undo the frame bolts from below which I was trying to avoid in order to not mess with the alignment. In hind sight I should have placed the engine mounts on the frame before lifting in the engine. Oh well – it only took another half hour under the vehicle to fix this.



A side note – After the block was in and the engine mounts tightened (total of 4 hours) I put a socket on the crank shaft and turned the engine to see if there was no binding and that the transmission and clutch were all still working After a few cranks I heard a loud POP! OH NO! sounded like I had just snapped something off. Im thinking something in the transmission?, Crank?, Piston? Anyway, just like anyone else, since I can’t figure out what it was – I just do it again! A few more cranks and again the loud POP. This time I notice the protective covering I had on the block deck to keep it clean was pushing out like a big balloon. Seems I had it strapped in tight enough that it created a seal so when the piston pushed up – it blew it out with a nice pop. Good news is that the engine works!

Now I get to go under and finish bolting in the bell housing and stiffeners

[Blackdog]

wow nice report, I vote for a sticky!! lots of good tips in here. Its almost like reading a step by step haha Thanks man!! hope it all works out for you!


STICKY!!!!!!!!

[Bill UK]

Totally agree excellent work, thanks for sharing it with us, top marks for the write up which must have taken time to document.

[oregonjoe]

While I was waiting for my head to come back from the shop, I worked on cleaning parts and doing some detail work. A friend let me come over and use his bead blaster to clean up the valve covers and intakes. Boy – what a fun gadget to have! Make everything look like new. Uses air pressure to shoot tiny glass beads and reach into all the places you can get sandpaper in. After about three hours, I had some nice looking parts. So nice in fact, I decided not to paint them like the original but just to clear coat them and keep the natural aluminum finish.

For the valve covers, I masked them painters tape and used several new razors and traced the relieved outlines make a cutout. Pressed the making tape hard along the edges to expose the outlines and cut away the material. Be sure to clean everything with Lacquer thinner before you mask.




Then spay with high temp paint in several very light passes. The trick is to get the paint carrier to evaporate between each pass which takes just a few minutes. It took about 10 very light passes to get it built up enough. The reason for this is that if you spray too heavy, the paint just builds up in the depressions and flows overt he top of the masking which is not what you want because when you try to remove the mask it will just tear the paint off with it. What you are trying to do is keep the paint just in the relief’s and not on the surface of the mask. Another thing I found is that the initial passes doesn’t stick to well and paint tends to run down hill. By lighter coats and waiting in between, it gets tacky and then next coats stick better.

Now here is the important part, do not let the paint dry. Wait only about 20 minutes after the last coat to peel off the masking. Again, if you wait too long, the making will be too embedded with the paint and just peel the paint off or tear the masking so you can’t get it off. Doing this while still wet (tacky) makes it real easy and gets a clean surface.

Once the mask is removed just a little cleanup is needed with some lacquer thinner and a CLEAN rag. Because the paint is just in the relief, any other paint can be removed by warping the rag around your finger and just wiping the surface – comes off real easy and leaves a nice clean edge.

When done with the clean up I sprayed several coats of clear high temp paint to give the surface a nice look and protect the aluminum from corrosion. The clear coat also helped clean up the lettering and make them stand out.



All the other aluminum parts a coat of clear coat too.

[jones123]

wow nice report, I vote for a sticky!! lots of good tips in here. Its almost like reading a step by step haha Thanks man!! hope it all works out for you!

[connormcd88MKIII]

Im in the middle of replacing my blown head gasket. These pictures are great. My #6 went too. Just wondering if you knew the torque settings when tightening the new gasket?

[cre]

Bolts = 75ft. lbs.
Studs = 90ft. lbs.


If you're reusing the stockers check thoroughly for bad threads, pitting, and measure to make sure they're still within spec.


NOTE!!!! Torque specs change depending on what you're lubricating the friction points with (Head, washers and threads of the bolt). Those I've listed are for use when using a GOOD moly based grease. Don't forget to chase the block's threads too!!!!