Engine rebuild questions

engines
geo
prizm

#1

I have to replace the rings and valves on my car. 93 Geo Prizm, 1.6. I want to do this without pulling the engine or crankshaft (time and money issue). From underneath, I can take off the rods. HOWEVER, you have to turn the crankshaft a bit to get to all the bolts on the rods. MY QUESTION is: Will turning the crankshaft mess up the TDC issue? I’m thinking no since the timing belt will be pulled. What’s the concensus?

MY SECOND QUESTION: Does anyone know of any specific issues to watch out for when pulling or replacing the valves and lifters (that might not be in the Haynes manual)?


#2

Turn it all you want, it will make no difference. The Haynes manual covers enough. Clean the carbon in those ring grooves and put the rings in the right groove.


#3

Don’t you think that if you are concerned with your ability to simply set camshaft timing,rings,valves,bearings (why not) are not your “cup of tea”

That is my consensus


#4

There’s a lot of things the Haynes manuals do not address and there are too many of them to go into here.

It sounds like you’re attempting what is called a “minor in-car overhaul” and these can be dubious even if an experienced tech did it; most of whom would refuse to do it in the first place.
If you want it done correctly then you’re looking at a multitude of tools (micrometers, cylinder hones, etc, etc) and the expertise to use them.

Simply throwing a set of bearings and rings into an engine is a crap shoot at best.
Just curious, but what’s the reason behind this project? Broken timing belt, oil burner, knocking, seriously overheated, etc.?


#5

Have you ever done anything like this? You always reset TDC at the crank before re-fitting the timing belt. There is no possible way to remove pistons without rotating the crank. And the head will have to be off, meaning not timing belt attached. This smells of a Newbie question, and your thinking too hard.

Also, get a ‘bottle brush’ cylinder hone. Failure to hone the cylinders will lead to advanced ring wear, or ring damage.
http://www.globalautoparts.biz/images/tool_images/flexhoneanchor.jpg

And for valves, take the head to a machine shop so they can properly fit the valves. Even with new valves, the seats need to be ground to match to provide a good seal. Leaks in the valve seats leads to burnt valves. Most shops can re-seat all the valves quickly and cheaply. At least I hope these valves use a single angle seat. Some use a multi-angle grind, which costs more.


#6

You can’t “rebuild” an engine in this manner and expect satisfactory results. The head must go to a machine shop for the valve job. The pistons will not “slip out” until you ream off the ridge at the top of the cylinders. After you hone the cylinders, check the ring end gap with one of your new compression rings. If it’s larger than what is specified, your are wasting your time…


#7

As OK4450 alluded, a “ring-and-insert” job is very difficult for a novice. A complete teardown/overhaul would be easier for a beginner. And I can’t imagine doing a valve job in the driveway.


#8

Alright guys. You started out as “Newbie” at one point, too. Just because I haven’t done it before doesn’t mean I’m COMPLETELY uneducated. I have been doing lots of research and reading and studying and asking questions, like this one. The reason I asked about turning the crankshaft is because the Haynes manual keeps saying “don’t turn anything” but that didn’t seem logical to me so I just wanted to double check with you guys. You have all confirmed my own logical thinking, so thank you.

OK4450 - expertise to use a micrometer??!! Can you read a ruler? Better yet, most of the nicer ones these days are digital, but finding one that goes to thousandths rather than just hundredths can be difficult -cuz that’s what I need.

Busted Knuckles - Is there a downside to using the long flat strips kind of cylinder hone compared to the bottle-scrubber type, cuz the long type is what Autozone has in their loan-a-tool? And thanks for the valve info. I do believe they are single angle. Just guessing but wouldn’t a multi-angle be on a VTECH?

Caddyman - Yes, I am getting a ridge reamer and I will clean the ring grooves. Thank you for your time-saving tip about checking the ring gap as soon as I pull the head off. I can see how knowing this first could save time and assist me in making sure I have the right oversized parts if that should be the case. But if the walls are WAY too worn, I agree that would be futile to continue.

Rod Knox - I will be in a garage. You need a clean environment to do this sort of thing.

There’s a first time for everything, guys. I do appreciate your help. I do have the number of a machinist. Oh, by the way, the reason for this is 251,000 miles and I have very little compression in one of my cylinders and gas is not burning and leaking into the oil and the plenum and coolant and what a mess. Needs to be done. And guess what - I’m a girl. We can fix cars too. We just have questions now and then like the rest of you guys. I’ll keep you all posted. Thanks again.


#9

None of us are being derogatory towards you. It’s just that in your original post you come across as not very mechanically inclined if you have to ask a basic question about TDC.

You mention doing this in-car overhaul without pulling the engine. I guarantee you, and etch this in stone, at 251k miles those cylinders are egged just like the crankshaft journals. Ridge ream the cylinders, hone it properly, and a new set of bearings and rings are not going to last long.

Can I read a ruler? Sure, but I don’t use one on cars. You’re even incorrect about micrometers. Nice, non-digital ones are available all over the place and personally speaking; I don’t like digital ones.
The “regular” ones are fine, and accurate.
And micrometers in “hundreds”? I’ve never seen a “hundreths” micrometer.

My point is that half a dozen micrometers, ridge reamer, hone, etc. is expensive, and then some. And for what purpose? New rings and bearings will have a short life on a non-machined crank and block.
Good luck anyway.

(Some other things to consider. Do you know how to inspect, REALLY inspect cam lobes, lash adjusters, etc. Do you know how to use Plastigage? (kind of pointless on a worn crank journal, but…)


#10

I should have added this about a bottle brush cylinder hone. If the cylinder is egg shaped then when you get done honing it’s still going to be egg shaped. The only difference is that you will now have an egg shaped cylinder with a cross-hatch.


#11

Given the mileage on your motor, I think you will find that it will cost you a lot less time (and probably less money) if you can find a used motor and swap that in for your current motor. Even a relatively high-mileage used motor would probably be fine for this car. I think you will find that this will save you an awful lot of aggravation also.

Doing a motor swap requires very few specialized tools (no micrometers, no honing, no de-ridging, etc). All you really need is your basic tool kit, a Jack (and stands), and an engine hoist (which you can rent). Most used engines come with things like harmonic balancer already installed, so you shouldn’t need pullers, impact wrench, etc. It is also much easier than doing an in-car overhaul (correctly (to the extent that it is possible to do it “correctly”)) and is much more likely to leave you with a working car when you are done.

I would strongly recommend used engine over in-car rebuild (assuming that you can’t afford to do a full engine rebuild right now).


#12

I remember going through a 2-year auto mechanics school back in the 70s and learned how to rebuild an engine properly. Even with that training, I still made mistakes. There are many judgment calls you’ll need to make when you’re inspecting all the parts. Without the underlying experience, how will you know if the level of rebuild you’re doing will last more than a few thousand miles. Too many of us have seen rebuilds that only last a very short time.

To the OP, please take OK4450’s advice seriously. He speaks honestly from the heart with a great deal of experience. (As do many of the other contributors to this forum.) I love the “can do” ambitious attitude in your reply, but please try to learn from the mistakes of others who have been in your shoes.


#13

The downside to using one of those long-flat hones is the fudge factor. The long-flat ones can give more uneven results in the hands of a novice, and result in a poor job. A bottle-brush hone gives a better finish and is virtually fool-proof. The major difference is, the bottle-brush hone has to be sized for your cylinder diameter, where the long-flat hones are adjustable in this regard, and can be used on a variety of diameters.

Also, a lot of high-end european and japanese engines use multi-ange valve seats. I know a '93 Geo Prism, actually a redressed Toyota, is not high end, but a lot of characteristics of high-performance engines have been creeping into the econo-box market for years. Just something I thought of to warn you about.

The fact your a girl has nothing to do with it. A job is a job. I’m worried that your trying not to remove the engine to do this considering you have a ‘dead’ cylinder. The chances of a ‘driveway overhaul’ fixing a dead cylinder in an engine with 251,000 miles on it are slim-to-none, and slim is waiting at the bus stop. I’ll bet the wear on this engine is excessive, and you’ll never get the cylinders right with a hone. The block will probably need to be bored to the next size, and oversized pistons used. This will require a complete tear down and re-build. I think your about to waste a lot of time and money.


#14

Hey OP . . before you even get started . . . have you checked the price of a good used engine in your area? I’ll betcha you can pick up a 100k motor for $500 . . . and have a blast installing it, changing out the stuff you would like to change (timing belt, water pump, seals, gaskets, clutch, whatever) and do it all for a good price. The chances of this good used engine are far better than ripping into the old 251k motor which will probably fail before the used one. Even if you are 100% successful with the re-ring and valve job . . . what about the rest of the motor? Those parts have 251k on them too, and this little 1.6 motor takes a lot of abuse to keep up. Especially since this is a $$$ issue, I’d go with a good used motor. Good luck! Rocketman


#15

I agree with you 100%. I once purchased a 1955 Pontiac that the dealer had overhauled. This overhaul consisted of new piston rings and a valve job. I had problems with this car from day one. I learned that this is really a sloppy patch rather than an overhaul. In those days, an oil filter was an option on the 1955 Pontiac and the one I purchased didn’t come with one. I had problems with the studs on the head that supported the rocker arms plugging up and then the rocker arms would chirp. I had to replace the hydraulic lifters. The car didn’t consume oil, but the engine always seemed to be out of balance. I could always detect a piston slap when the engine was cold. IMHO, it is better to run a worn engine until it quits and then either have a professional rebuild or have a remanufactured engine installed.

Apparently, Ford motor company agrees with me. I had a Ford Aerostar that had a cracked cylinder head and coolant leaked into a cylinder. The van was under warranty and when the service manager informed me of the problem when they tore down the engine, I asked if they were going to replace the head and hone out the cylinder that was affected. The service manager said “No. Ford policy is that we replace the engine”. I certainly didn’t object.

I will confess to using the sloppy patch overhaul method on my 2 cycle LawnBoy mowers that I used to own. However, there were no valves and the cylinder wall was tapered so I didn’t need a ring compressor. I just roughed up the cylinder wall with a little crocus paper, pushed the piston back in the cylinder and called the job done. I could get another season out the mower. On the mowers I have now, I just replace the engine. It makes more sense.


#16

Even if the OP was perfectly proficient in performing a proper complete overhaul and there was no outside labor paid other than auto machine shop sublets this job would still not be cost effective.
By the time they paid for a head rebuild, block vatting/boring/freeze plugs, turned crank, new oil pump, new piston set, and more than likely a new cam along with a dozen other things the costs would be more than the value of the car.

A quick look at a set of oversized pistons shows that a simple 4 piston set is almost 300 bucks alone.
An old Chevy small block is cheap to build but it seems the smaller the engine and the fewer cylinders involved always translates to a much higher price.

OP, you can certainly throw a set of bearings/rings in there, redo the head, and it may run fine. The only questions are for how long it will run and how much oil burning and knocking will it do.

If I’m going to perform engine measurements in “hundreths” then I might as well use a yardstick. :slight_smile:


#17

Hey guys, thanks for the feedback. I agree it would be easier to JUST go out and get a new engine, but I don’t have $6 or 700.00 for that. I could only borrow 300 for parts and someone else is helping with money for the tools. The tools are all loan-a-tool through the auto shops, and yes, a few that I have to buy. But that’s all I got, and if it gets me a year or more - great. Maybe by then I’ll have a job and more money to do it right. But my boss went bankrupt and I’m screwed.
Now, once I get the heads off, I’ll be able to see and measure everything and see what the condition of everything is. Until then… I will go to a machine shop, but I need to know what is out of spec and by how much before I walk in the door and get ripped off. And I need to be able to measure things when it comes back and see if he did it right.
Yes I know how to use Plastigage to check for oil clearance, thank you for checking on that. It is important. And I am replacing the freeze plugs - they’re only $9 for the set.
Does anyone know where I can find a telescoping guage to check the cylinder width? I can’t find those anywhere. Are there any “jerry-rigging” ways of doing this in a pinch if I can’t find one? I’m in L.A.
Thanks again.


#18

The problem is you might put your last cent into it and it might still not work, then you will be in a mess. Good luck!


#19

The tool for checking the cylinder bores is referred to as an inside micrometer or bore gauge set.
It’s unlikely that you will ever find anyone renting something like this because they’re expensive and can be easily ruined in the wrong hands. There’s no jerry rigging around this.

Besides, even if you measure the cylinder bores you’re not going to like what you find. That will be a need for boring; about 99% certainty.
Considering the amount of money and the situation, you’re probably better off to NOT measure the cylinder bore or even Plastigage the bearings.
Same thing with my blood pressure. I got tired of hearing my wife and doc whine about it so I quit taking BP medicine or checking the BP. Never a worry since I don’t know what it is in the first place.

Trying to make the best of this here’s a few tips.
When honing cylinders keep the hone moving up and down at a moderate pace, occassionaly spraying a little mild lube on the cylinder walls. (Gum Out carb cleaner, mineral spirits, etc.)

Be SURE to clean out all of the piston ring grooves thoroughly. I have a ring groove cleaner tool but a piece of broken ring works much better IMHO.
Make sure the rings are installed with the correct side up, stagger the end gaps as recommended, and make SURE the rings move freely in the grooves. Check the ring end gap. Too tight and when the engine gets hot you will be in big trouble.

Make sure the cylinder head is flat. A valve job should be performed but an auto machine shop will probably hit you for 125 to surface a head and grind the valves.

I would advise spraying the new head gasket with Copper Coat. This aids a lot in head gasket sealing.
Torque the head bolts in stages along with the rod bearing caps. (Do not mix the caps up and make sure they go back in exactly the same place they came from.)

What I always do with rod cap bolts/nuts is Loctite them AND use a sharp chisel to stake the edge of the nut/threads. Just a little insurance to prevent loosening.

Something else I do and it has worked very well for me over the years. Torque the head bolts in 3 stages. Allow it to sit (preferably overnight) and then retorque them again. Often you will find that the gasket and bolts have “relaxed” overnight and what was correct the day before is not so correct today.
Anyhoo, hope some of that helps.


#20

no offense but 300.00 seems to be nowhere near enough money to buy the parts. your talking a complete gasket/seal set, rings, bearings,freeze plugs. are you doing rod and main bearings? how about cam bearings? they are just as important to replace as the other bearings to maintain proper oil pressure to the valvetrain. if the main and rod journals are eggshaped the bearings won’t do alot of good. if you are reusing the rod and piston assembly make sure they are reinstalled in the same cylinder that they came out of.if you put #1 rod and piston assembly into #2 cylinder and vice versa this engine won’t run very long.also make sure you put the caps on the mains and rods correctly or they could spin destroying the engine. hence the term “spun a bearing”