Vtec04

All 3 of the engines I rebuilt would not fire right away. They would crank quickly like they had no compression. Then they would sound like they had uneven compression. They would have to crank for about 30-45 seconds before they would have enough compression to start. The reason is not because the cylinders had no oil to seal the rings either, because I put 1 capfull of oil in each cylinder through the spark plug hole before cranking it for the first time. Why is this? Thanks.

ShinsenTuner

iTrader: (1)

For my engine it fired up right away without any hesitation. I only cranked it a few times for a couple of seconds to build oil pressure then went right for it. I didn't do the capfull of oil in the cylinders either - first time ever hearing of it TBH.

Vtec04

I thought a little extra lube for the rings before it built oil pressure wouldn't hurt.

gtpilot

But it has to burn all of that oil off and it then is covering the combustion chamber with carbon? What did you use to lube the cylinder walls with when you installed the pistons in the holes? I always use WD40 and they always fire right up...

toyomatt84

iTrader: (1)

Did you pressurize the fuel system before cranking? (Turn key to Ignition and wait a bit for the fuel pump to pressurize fuel lines.)

I've never had that problem, regardless of what engine I rebuilt (Honda, Ford, Toyota, and GM experiences).

motoxxxman

sounds like you're not rebuilding these engines correctly. are you getting the cylinders bored/honed for oversize pistons and rings? are you setting the piston to wall clearance properly? are you setting ring gaps properly? are you lubing the cylinders as you assemble the motor? what are you lubing the bearings, cyl walls, and valvetrain with during assembly?

snobordboy

I agree with the previous posts, you should be lubing the cylinder wall during assembly, I just use the oil I will be breaking the engine in with, but assembly lube for the bearings and head.

Are you priming the fuel and oiling systems before you try to fire it? You should be giving short cranking periods until you get the oil light to shut off, and allowing fuel to build proper pressure all the way to the injectors, before firing it.

Vtec04

Yes, I cycled the key a few times and then loosened the banjo bolt on the end of the fuel rail until I got fuel out. I do not think that running air through the injectors is good for them.

Vtec04

Well, I must be doing something right. They always had great compression and ran great once they were broken in. I lubed the bearings and valvetrain with Federal Mogul engine assembly lube and I sprayed the cylinders with Liquid Wrench Lubricating Oil while honing the cylinders and before installing the pistons, but I was worried that the oil may have evaporated or ran off, so I used motor oil to lube the cylinder walls before starting it.

motoxxxman

that only answered one question. I asked several questions. please answer them all. and liquid wrench is NOT a good lube to use for the cyls for assembly (it does work well for honing though). Adding oil through the spark plug hole does absolutely nothing for lubing the cyl walls, just so you know. And now a new question: how well did you wash the cylinders after honing?

Vtec04

I had a machine shop check the clearances and they were all within spec. Also, I washed out the cylinders very well with brake cleaner and a soft brass brush. Lightly using a soft brass brush on iron cylinders will not do any damage. I re lubed the cylinders with Liquid Wrench and lubed the pistons and rings with motor oil.

ShinsenTuner

iTrader: (1)

Injectors in their simplest idea is just an electrical cylinder that opens and closes; why would running air through them at a short burst damage them? Just curious since most cars I imagine do not have fuel sitting in the rails all the time waiting to be used.

Vtec04

I understand the concept of how an injector works. I also believe, perhaps not true, that the gasoline helps to lubricate and cool the injectors, like the fuel pump. I figure purging the line can't hurt and could help. Actually, all cars with MPFI that I know of has fuel sitting in the rail at all times waiting to be used, unless you have a leak or run out of fuel.

toyomatt84

iTrader: (1)

Some injector designs (like the powerstroke diesel application) have high pressure oil forcing oil through the injector. And, when the balance of fuel is off, or the fuel is dirty, or the oil is bad... you can actually damage the injector.

ShinsenTuner

iTrader: (1)

I learned something today. Thanks guys

Vtec04

Anytime

TomCat39

This is not the way you are supposed to wash the cylinders after a hone.

It's very clearly indicated that brake cleaner is not satisfactory to actually remove the metal dust from the cylinders.

You are always supposed to wash the cylinders with soap and water after a hone then dry them and oil them immediately after drying. Then begin assembly.

Vtec04

I cleaned the whole block with soapy water after I took it to the machine shop anyway because it had metal shavings in it from when they resurfaced the head sealing surface. I just used brake cleaner to cut the oil.

TomCat39

I gotchya, the way you put it was you did the brake cleaner attempted clean after honing.

I was surprised no on else commented on that.