Rebuilding the engine - what parts to use?

[Apolan]

So as i scrambeled some money together i figure its time to do some research and finnaly get to rebuilding my engine. Its broken (i suspect due to oil deprivation in the con-rod bearings, or because the rods "sat" on the crankshaft pins.). Anyway the engine needs rebuilding. Its a blutetop,bigport,tvis,map,3rib.

So now what exactly do i need to do, how to do it, what to be careful about and where to get the requred parts the cheapest (or what brand) yet still reliable.

Here is what i think:

- 4 new conrod bearings
- 5 new main bearings
- new bolts right? what kind?
- new "semerings" (dont know how thats called - the brackets that hold the oil in )
- polishing the crankshaft
- new gaskets (oilpan, exhaust, intake)
- check whats up with the oil pump, replace if neccessary
- new timing belt (just in case)
- new spark plugs, filters, oil
- a bloody VDO oil pressure gauge

So how do i know which bearings to use? Should i have the crankshaft measured after its been polished and choose acordingly, or should i set a size and have the crank polished/grinded to that spec?

The other thing im wondering about is should i also overhaul the upper part (not the head) - but honing the cylinders and getting new rings - eventhough its working just fine?

Thanks in advance. Hopefully ill get to drive my baby soon.

[BenR]

The amount of damage to the crank will dictage just which bearings you should use. IF it comes to it, it might have to be reground so much that you might have to junk it.

You will want to regrind to the nearest next bearing size since there isnt a large array of bearing thicknesses.

If you fitting new rings, then you have to have a new hone finish.

[robokill]

Hey Apolan here are some list specs.

If you wanne do it right to go all the way.

New pistons ... (81.5mm bore with 18mm pin)
Oversize the lower block to 81.5mm
You will need new bearings for the conrods

Do a mot on the oilpan for an oil temp sensor
bolts can be standard (4age can be reused without a problem) If you want new buy the ARP bolts.

Only buy gaskets at toyota as they are very good. (very important is the headgasket. The junk from ebay is not thin steel but some paper kind of thingy)

spark plugs what I heard from R.Hellenbrand (here on the forum) is to buy the magnecor ones. They seem very good if you use iridium spark plugs.

Did you have any difrent camshafts? If so maybe buy a thicker timing belt.

Go run on 5w 40 full synthetic. Don't go more than half trotthle with the first 1000 km do an oil change then and then start really driving it.

Then you have an engine which runs good and is good. If you have any damage I would go oversize pistons so that it will look like new.

[oldeskewltoy]

INSPECT! INSPECT! INSPECT!

DON'T BUY ANYTHING YET!

Do you have a factory service manual? Borrow one if you can.. READ the engine section like your LIFE depended on it, Now read it again. There are processes and procedures that can screw things up if you don't know what you are doing or in what order they should be done......
for example... more than 1/2 the people I know who has rebuilt their own engine... didn't know there is a procedure for cylinder head removal... doing it wrong could lead to warpage....

Good old fashioned expereince helps too... for example... 2/3 of 2 egg cartons become perfect recepticles for bucket/shim. That way *IF* you don't replace cams... you likely won't have to reshim the whole thing.... If you are replacing cams... it is a good idea to measure and know how thick each shim is(mark each shim).... it goes a LOOOOOONG way later in helping you adjust valves....

When ever you rebuild the engine... new oil pump... new water pump.. (and in AE86 case... new metal plumbing parts) should always be considered... Have you chosen a machine shop? At the very minimum you'll want the block tanked(cleaned) and oil galleys opened, cleaned, and resealed.

Basics... from the bottom - pull the pan... begin looking at the rods, begin with #4, then move forward. The reason #4 is first, is it is the last crankshaft point to get oil... #4 rods fail more often in a 4AG then other rods. If the rod end is blue.... chances are its junk... Blue means it has run an intense heat cycle. Mains are not usually a problem with a 4AG. I've seen 2 blue rods on a 4A engine and the mains were still all perfect!

Basics... from the top - remove all ancillitory items(cam covers, t belt, rear covers...) strip the engine so the head can come clear EASILY. Be careful with the cam journals and the bolts... they are fragile - follow factory service manual procedures. Also... since you read the book... you also know each journal cap is marked with where it belongs on the engine. Find the loosening procedure for the head, follow it. Remove head, look at cylinder bores. look at piston tops, ESPECIALLY around the piston edge. Look for crumbling

There is still more inspection required... but... if you haven't come across any problems yet... NOW you can begin to think of buying some parts.... but don't go too far... you still need to strip ALL the parts from the block and measure EACH cylinder bore in at least 3 places, you'll need to check the head for flat.

On to the head - the cams are already out(required to pull the head off)
OH... DON'T forget/lose the washers under the head bolts!!! They ARE REQUIRED!! An oldeskewltoy fuck up... trying to help you avoid
Remove shim/bucket assembly, follow the trick I point out above... or some other way to keep things organized. Now the "tough" part, there aren't many valve compression tools for the 4AG... Use a 5/8"(16mm) spark plug socket...[13/16"(20.5MM) can also be used] and follow illustration below. Then use a palm rachet to put pressure on the retainer, to allow the keepers be removed... This same tool can be used to reinstall the keepers the only other "tool" needed is a balled up cloth that you can stuff under the head to hold the valves in place.



Do one valve at a time... I'd mark each Intake valve on its face using I1, I2, I3 thru I8. I do the same for exhaust valves. As you remove each valves keeper you can put them in with the bucket/shim. remove all valve springs, retainers, seats. Check each valve-to-guide clearance, compare to FSM specs....

There is more... but you get the idea....

Once everything has been checked... THEN you buy..........

[Apolan]

Much thanks for the help, i appreciate it alot. But i was thinking of leaving the head alone, since it works just fine and i really dont have the money or the experteese to start messing with that too.. The importaint thing for me is that i get the engine into solid running condition, so it will last a couple of years of normal abuse (that meaning occasional spirited driving, and perhaps a mild track day every once and a while).

There will be time for me to really get into things,perhaps think about swapping in a 20v or tuning this one; but for now i just wanna drive and experience the car as it is. In couple of years time ill study this more accurately, and then it will be time for doing things right.

For now i just want to have a reliable engine that would preform decently and enable me to lern on the car dynamics and all that, sice i didnt get the chance to do it (enough) before.

So can i just fix the bottom (meaning the bearings, crankshaft, oil-ways), or will that just not be enough?

[oldeskewltoy]

Apolan Wrote:So can i just fix the bottom (meaning the bearings, crankshaft, oil-ways), or will that just not be enough?

I'm not there... can't tell you. MOST of what I said... to just above the pic... holds true for the block...

There is no easy or quick way to rebuild an engine and call it reliable... What about finding a used engine, or short block? "short block" - means the bottom of the engine with all the parts in it. The advantage to a replacement is you then can take your time rebuilding the lump you have... while the used engine powers you over a year or so... That should give you enough time to collect the funds to do a proper rebuild on your spare engine

[Apolan]

thought about that too; was already talking about buying an engine from somebody, but then again this "new" engine can be just as bad as this one, on the virge of breaking down. so i thought i might as well fix this engine for me to gain experience and then in couple of years when ill need a bit more power maybe buy a 20v engine or a 7rib smallport and tune that..

But i get the idea, i need to first inspect the status, and then ill report here. Hopefully i can get a mechanik at toyota to help me out a bit.

Just one more thing.. if i do decide to take the head off and replace the gasket, can i use a thinner one with no other implications and complications?

[oldeskewltoy]

Quote:Just one more thing.. if i do decide to take the head off and replace the gasket, can i use a thinner one with no other implications and complications?

You can.... but the thinner you go... the more you will change camshaft timing.. now if you added cam gears and adjusted the thinner head gasket out of the equasion... then it would be fine.... OEM is 1.2mm

[Apolan]

Couple of questions..

What is the easiest way to pull out the engine? Do i need to take the trannsmisiion off first from underneeth or is there enough space in front too push the engine off the drivetrain? also can radiator stay inside or will i have to move it?

Once i have the engine outside (without oil and water in it), i will flick it upside down, put it on the cam-covers, unbolt the oilpan etc.. then disconnect the con-rods. Can i just lay them gently down on the valves or will that damage guides or whatever? The idea is to replace just the bearings without oppening the head or taking it off. Also can i re-use all of the bolts or do i need some new (for the con-rods..)?

Also i would like to inspect the oil pump, if it is working correctly. How that be done?

And the last question, do i have to short any terminals prior to checking compresion on the engine (while it is still inside the car)? I would guess not, but just to be sure.

[Ivan141]

You can pull out the engine with or without the gearbox.. but in both cases the radiator must be taken out.. it would probably get in the way, and certainly get damaged otherwise.
You dont need to short any terminals for a compression check, but unhooking the igniter from it's signal source might be a good idea.