What do mechanics do when they rebuild a gasoline engine?

Question

My Hyundai has 150,000 miles and the first owner beat it to hell. It burns alot of oil; everything else is fine. If I told a mechanic to "rebuild" my engine, what will they exactly do? What kind of parts are recommended that I change when rebuilding an engine? How much will it cost on average?

Answer 1

In your Hyundai is a well-built engine. The oil burning problem might not necessarily be a worn out engine. Take your car to a reputable mechanic or go and buy a compression guage. If you have only limited tools this guage can tell you a lot about an engine. Remove all of the spark plugs(keep track of where the plug wires are hooked up). Screw in compression guage and turn car over for 5 seconds. Write down these readings for all cylinders. Take an oil can and squirt 4 or 5 drops of engine oil in each hole and repeat the compression test. If the compression guage reads higher with the oil squirted in then the engine has ring wear. If it doesn't then it probably has valve problems. If compression is less than 80% than the engine will need to be removed, disassembled, measured, and machined if worn. Usually piston rings, bearings, timing belts or chains, timing gears, gaskets, oil pumps and soft plugs are replaced when overhauling or rebuilding an engine. Since your Hyundai is imported it will be expensive. Consider selling or trading the car because it probably isn't worth doing that much work to. You might also consider a used or remanufactured engine to replace your existing engine. Used engines are relatively cheap compared with rebuilding but they might be in the same or worse condition than yours. If you have mechanical ability and tools they make plenty of repair manuals that will walk you through the process. If you have never done anything mechanical then you should probably go to a reputable mechanic or dealership. I wouldn't have the car overhauled if the repairs cost more than what the car is worth.

Answer 2

Well a good mechanic would find what the specific problem is. If a rebuild is necessary, he will need all the gaskets,moveable parts, and possibly boring the cylinders. He may need to take the engine out and send it to a machine shop that can bore out the cylinders. You could have just a gasket problem. But if the engine needs to be rebuilt, you would want to consider buying a rebuilt engine or a salvage engine... both with warranties and price is around the same. It can take less time overall with a rebuilt/salvage engine than to rebuild. But if you know the mechanic well and he/she is really is good, trust he/she. I say she because there is good female mechanics out there.

Answer 3

an engine overhaul is a rather complicated task if you don't know what you are doing. Detail in this endevor is key you must have exact specs if you want it to turn out right. now i could give step by step instructions but I can't sit here that long my best advice for you is to let a pro handle it it would cost you a grand and a half, two grand if they ovehaul to manufacturers specs. now if you are wanting to attempt this chore on your own i would recomend that you try and find a guide for your engine, a good parts store may have one or you may have to go to a dealership, or you might even find one on the net. but make sure you know what you are getting into before youtry this at home. in most cases if you do it yourself using stock parts and you have all of the right tools and the cam and crank are ok, you can do it for about a grand.

Answer 4

Hopefully, he'd trade your old motor in for a factory rebuild. There's now way some guy in a garage can do the same job a factory would. The mechanic would probably just replace bad and worn parts, while the factory would replace everything that can wear out.

Answer 5

Piston rings.valves and seals,shave the head(s) or replace them,same with the block,etc.Cheaper to replace the engine sometimes.But a Hyundai? Cheaper to replace the car.

Answer 6

a Hyundai is a disposable car don't waist money rebuilding it..
you wouldn't rebuild a Bic lighter

Answer 7

Brian said it all, great job Brian

Answer 8

Cleanliness cannot be over stressed!

The first step in the cleaning process is to clean the area in which you are going to assemble your newly machined engine.

Next completely wash engine block:

*Re-move galley plugs & brush out all oil galleys.

*Use soap and water to wash out cylinders then completely dry with air & linen (no lint), and use light oil in lifter bores, main bore, cylinder walls, etc., after washing.

TOOLS

*Tools that will be needed are: engine stand, torque wrench, ring compressor, hammer with plastic or wood handle, wrench & socket set, assembly lube, oil, gasket sealer, oil pump primer, engine paint, galley brush set, freeze plug installer, thread sealer, engine turning socket, and a lot of patience!!!

*Brush out oil holes in crankshaft!

*Arrange engine & engine parts in order of assembly

*Install freeze plugs, cam plug, and all galley plugs. (You may want to paint back of block).

*Mount engine block on suitable engine stand and turn up-side down.

*Install camshaft first, being especially careful not to damage cam bearings. Use engine assembly lube on cam bearings, and camshaft lube on camshaft.

*Install main bearings in block & lube with assembly lube. (High pressure lube)

*Lay crankshaft into main bearings for clearance checking purposes.

*Place a piece of plasti-gage lengthwise across main journal then install main caps & bolts and torque to specs.

*Dis-assemble what you just did and check your clearance using the paper the plasti-gage came in, the spaces on the side of package is your clearance.

*Install the rear main seal (if a two piece rear seal is being used, it will have to be installed in block and cap before crankshaft is laid in block) . Be sure and follow instructions in your gasket set for seal installation.

*Clean plasti-gage off crankshaft and place crank back in block(be sure not to forget to install your rear seal). Install main caps and bolts, and torque all caps down to specs. except the thrust bearing cap. You now need to set the thrust on that cap if it is not pinned! To set thrust, just barely snug bolts to that cap, then use a hammer and (on a counter weight) hit the crankshaft to the rear of engine, then to the front of engine last, then torque that cap down to specs. and check end play of crank. Most crankshaft thrusts are between .004-to.010 end play.

*Install timing chain and gears. Now is a good time to degree in camshaft. Click on degree camshaft at left of page.

*Oil wrist pins in pistons heavily, install rod bearings, install rings on pistons. There is a certain sequence and placement of rings not covered here.

*When removing rod caps, a suitable rod vise is required so damaged is not done to connecting rod.

*Turn engine right side up and oil all the cylinders, rod bearings, pistons and rings, and crankshaft journals. Use oil (30 weight) on pistons, rings, and cylinder wall, and engine assembly lube on crankshaft and all bearings.

*Install a suitable ring compressor over piston (be sure rings are correctly placed on pistons), install plastic or rubber boots over rod bolts (so you don't scratch cylinder walls or nick the crankshaft), place the first piston in hole, tap the piston in cylinder using a wood or plastic hammer handle. As you are tapping piston down into the hole, be sure and center the rod bolts over the crank journal or damage will result.

*If you want to (and you should) check rod bearing clearance, there are several ways to do this. If nothing else, you should plasti-gage before oiling crank or bearings. Then clean off plasti-gage and do the steps over again.



*Install rod cap to that con-rod (do not mix up caps from one rod to another) {be sure they are #'d in pairs before dis-assembly}. Bearing tangs usually (but not always) face each other. Do not put cap on backwards or damage will result! Also pistons and rods are directional and can be installed in only one (correct) direction! or damage will result!

*Install rod nuts with proper lube and snug nuts only at this time. Install the rest of piston and rod assemblies in their proper cylinders.

*Torque all rods nuts to torque specs. either by ft.lbs. or the bolt stretch method, after all rod and piston assemblies are installed.

*Turn engine back upside down and install timing cover, oil pump (be sure and prime pump first), oil pump drive rod, pick-up screen (be sure it is new or perfectly clean inside and out, oil pan gasket, timing cover gasket, timing cover, and oil pan (sealing it properly).

*Turn engine back right side up and install cylinder head gasket (s), cylinder head (s), and bolts, (some head bolts require sealant) and torque heads to specs. Install valve train components, set vales, etc. and install intake manifold and bolts. Be sure that deck and all surfaces are clean and free of oil.

*Tape off any areas that you do not want painted, and be sure you put something in spark plug holes, and paint the engine. Use engine enamel.

*Install oil filter adaptor and oil filter, and oil in engine. Use 30 weight oil for engine break-in.

*Prime engine (with suitable tool) with drill motor, while turning engine over by hand with a suitable tool until all rocker arms are oiling. All oil galleys must be full. If you cannot prime engine, then you need to fill all oil galleys with a tank filled with oil mounted to the oil pressure switch hole. At very least, do not crank engine over with spark plugs installed if the engine has not been primed! We use an oil pressure gauge to check oil pressure when priming engine.

*Install valve cover(s). It is usually best to seal gasket to valve cover, not to head so valve cover re-moval is more simple if it ever has to come off.

*If you haven't painted engine yet, clean off any spilled oil on block or parts to be painted, then paint what you want with engine enamel.


If you made it to here, congratulations


Your engine should be ready to install