[RESOLVED] Piston install from the bottom? [Merged 5-9]

[idt512]

are there any short cut methods in removing pistons? I was thinking dropping the oil pan and unbolt the connecting rod and bring it down along with the piston, is this possible?, any clearance issues? I just bought my 1st DSM and found out i have 3 cylinders that have low compression, added oil through the spark plug holes and compression shot up!

 

[Defiant]

There's that pesky crankshaft problem....

 

[MNGSX]

They won't clear the main cap web on either a 6 or 7 bolt block... Nor will they clear 1g squirters.

 

[ItsStockOfficer]

Originally posted by Defiant
There's that pesky crankshaft problem....

 

[idt512]

So can I remove them from the top by removing the head and then unbolting the rods through the oil pan? I dont wanna dump too much money into it just yet as I am unsure about the condition of the rest of the car.

 

[Cablefed]

Thats the only way to do it. If your putting new pistons in you may want to get the block honed if the cross hatch is not that good or if you have a little bit of taper. Good Luck!

 

[DJDohBoy]

Is it posible to replace a piston, by just dropping the oil pan. I am Trying to find a way to replace a piston without pulling out the engine, does anyone have an easy way of doing this, or does then engine need to be taken out?

 

[BUCK]

Pull head & oil pan.

 

[awd4g63]

Unless you're taking out the crank, you'll have to yank it from the top of the block. And if you're pulling the crank, save yourself some time and pull the engine.

 

[Defiant]

The pistons won't come out the bottom, you have bearing support webbing in the way. See post 2.

 

[cbrfrenzie]

Hello all, I spun the #4 rod bearing in the 4G63 after 27 miles of break-in, and fresh rebuild. I do not want to take the head off, as I will ruin my $120 ICS Titian head gasket. The rod is toast so i need to get it out and weigh it for a replacement from Eagle. I was wondering if anyone had any experience installing a piston into the cylinder from the bottom of the bore, rather then the top. I need to replace the crankshaft, so it would be out of the way. Looking at it I think it would work, with the crankshaft out of the way of course. This would save me valuable time and money, as the entire timing system could stay in place.

 

[93_tsi_fwd]

It could work, but how are you going to get the rings compressed so that it wont hit?

 

[delta448]

This would save me valuable time and money, as the entire timing system could stay in place.

Captain Obvious says... -the timing system cannot stay in place if you remove the crankshaft.

I suppose it's possible to put them in from the bottom, and probably could even be done with moderate success, but I wouldn't risk an engine to save $120 on a headgasket. The cylinder bores are tapered the wrong way for a bottom installation, and if you use a tighter ring gap than the taper will allow, you'll score the cylinder wall and that can destroy your engine the first time you fire it up. That or you'll just break a ring.

 

[cbrfrenzie]

Captain Obvious says... -the timing system cannot stay in place if you remove the crankshaft.

I suppose it's possible to put them in from the bottom, and probably could even be done with moderate success, but I wouldn't risk an engine to save $120 on a headgasket. The cylinder bores are tapered the wrong way for a bottom installation, and if you use a tighter ring gap than the taper will allow, you'll score the cylinder wall and that can destroy your engine the first time you fire it up. That or you'll just break a ring.

I'm retarded, I didn't think of that.... hahahaa. The thought popped into my head and i couldn't find anything searching. Thanks for pointing that out .

Why would the cylinder bores be tapered? Do you know the factory specs for the taper of the bore? When the block is bored oversize, is it common practice that the machine shop doing the work would taper the bore? The only thing that comes to mind is a block with some miles on it might have a ridge at the bottom of the bore, where the rings don't come into contact with the bore, but I've never heard of a tapered bore.

Has anyone done this before?

 

[delta448]

When the block is bored oversize, is it common practice that the machine shop doing the work would taper the bore? The only thing that comes to mind is a block with some miles on it might have a ridge at the bottom of the bore, where the rings don't come into contact with the bore, but I've never heard of a tapered bore.

So I'm guessing the engine was bored when rebuilt? If you've had the engine bored for oversize pistons and only put a few miles on it you probably won't have to worry about the taper.

Cylinder bores don't wear the same from top to bottom, they wear more heavily nearest the top travel of the compression ring and usually very little towards the bottom, if at all. There is more pressure on the rings and less oil present at the top travel, so the bore always wears unevenly. You can usually see and feel the ridge the compression ring created when it stopped moving up and started moving down in its stroke. There is almost never a ridge at the bottom of the ring travel.

 

[blcknspo0ln]

It would take more time and effort to try to do a swap like that with the engine in the car versus taking it out. Besides, if you've spun a bearing, chances are the block will have to take a trip to the machinist anyway.

 

[Defiant]

You'll need a splay wedge to spread the bearing webs far enough for piston clearance. Make sure it's a hydraulic one, as the manual screw-splays take forever.

Oh, and this will crack open your block like a rotten jack o' lantern, so you'll need a new one of those, too.

Just wow. Have you people ever seen the bottom of a block?

 

[99gst_racer]

Yeah, it's definitely not possible to remove a piston/rod through the bottom of the block, even with the crankshaft removed. The mains overlap the cylinder bore and that will not allow the piston to pass through.

Sorry bud. You got to bite the bullet and pull the head.

 

[delta448]

I should have realized the mains overlaps the bores and would block access, much more of a problem. From my own gallery: 4g64 At Teardown - DSMtuners Gallery

 

[soldave]

So I'm going to be taking my first look at the engine at the moment with a view to removing piston 3, checking there is no damage to the cylinder wall and getting a replacement thrown in there. However, I've heard conflicting stories about how I can do that. Some have said I can actually go from the bottom if I drop the sump out of it and do other bits. It sounds a little messy, but would mean the head can stay on the engine and would probably require the fewest number of parts to be taken off.

Other opinion is that if I go from the bottom the crank, oil pump pickup & squirters need to come out, and the front case needs to come off to get the crank out, which sounds like an absolute swine (probably one with flu). Question is, which one is correct and how should I be aiming to get the number 3 piston out?

Thanks for any advice you can offer me

 

[crimsondragon]

No it won't. Please don't do that. The front case and rear main seal are still holding the crank in. Your best bet would be to judge how much clearance you have, move the crank till #3 is at BDC, separate the rod, push the rod up and around the crank throw while simultaneously adjusting the crank to move the throw out the way to clear the piston.

 

[dsm-onster]

Save yourself the headache and pull the head. It's actually easier on you looking down and working instead of looking up in the engine bay from below and working. drop the oil pan remove the caps (keep them matched to their rods). And push them out of the top. I don't see how you can get the pistons with rings on it back into the cylinder going from underneith anyway. I guarantee you a spring compressor won't work if you try to reinstall a piston that way.

I'm fairly cetain the counter weights will be in the way once the crank throw or stroke is out of the way.

If you're main bearings arn't bad, then you should not pull it apart. You're just adding one more risk factor (contaminating any one of the main journals, improper torque of the main bolts, front rear main seal leakage, B-shaft bearing contamination, crank case gasket leak dropping oil pressure to dangerous levels, etc.). An new head gasket and proper arp head stud torquing is far less expensive.

 

[HIGHPSI4]

You can not remove the piston out the bottom even with the crank removed. The piston skirt hits the main journals.