What Should I Expect in an Engine Rebuild & Why Does it Cost so Much
I get these questions all of the time- It costs what to rebuild my engine! or Why does your engine rebuild cost more than theirs?
I am going to try to answer some of those questions here and try to make you more aware of the difference between an engine rebuild and a freshened engine and I am also going to try and show you the difference between a correct engine rebuild and not.
First what is the difference between a rebuilt engine and a "freshened" engine. If you rebuild something be it an engine or anything else, you do just that REBUILD IT - ALL OF IT. Typically a freshened engine, which unfortunately many class as rebuilt, is just that. It has some new parts, usually rings and bearings, it may have a quickie valve job and it will have a new pan, head & valve cover gasket. If you are lucky it may get a new front seal and perhaps a rear seal. So whatever is inherently wrong with the engine still is. Crank issues, warped block surface, dirt plugging cooling passages, too much taper in the bores, slightly twisted rods or bad small end bushings. This type of rebuild was very common in the 60's & 70's when you were trying to squeeze a little more life out of an engine on a car that really had no intrinsic value - remember back in the early 70's you could buy a turn key running XKE series one for less than $3500.! A 427 Cobra for 10K! Different times different thoughts. If someone told you it was going to cost you 13Kat the low end to get into your 7 series BMW you would dump it and find something else. 20 years from now?
So what is entailed in a correct engine rebuild? First and foremost is a sit down with your engine rebuilder to discover how they plan on rebuilding it and what you want to get out of it - Do you want more horsepower? Perhaps modern Electronics, are you showing it as a 100 point car or is it going to be a street car. After that is out of the way what does your engine builder plan to do and why
First thing first, (we are going to use a 1969 MGB engine here for an example) out comes the engine and it is pulled apart to get it's first real visual check. At this point it is the first time you get a chance to get a handle on any unexpected issues. Here is where you will see the big things, a broken crank, a crank that has been turned too many times. A block that has been bored before and has now worn past the point of a rebore. You will also get to see any obvious cracks in the head or block. This is a time your rebuilder should be talking to you. Telling you what they think and at a minimum where they are going next - the block will need to have liners installed as it is bored and worn beyond use or the crank will need to be replaced, etc.
Now many of the parts will move over to the machine shop and be further cleaned and tested. To truly clean a block correctly you will have to rebore the block when you are done. So you already have that cost in the bill. To completely clean a 4 cyl iron head costs around $45, to then magnaflux (a way of looking for cracks) the head will cost another $40.00. Assuming that it cleans up and tests well it will cost around $100 to have the head resurfaced. The head is now ready for a valve job. It is going to cost around another $100 to have 8 new guides installed, figure around $50.00 per new valve seat (and unless previously done or on a head built after 1978 you will need to replace the exhaust seats to meet the requirements of new fuels) then add another $150.00 for the labor of the valve job. So to recap here just in the work so far on this engine - we removed the engine - $450.00 we then disassembled everything and did the first cleaning and check out, $360.00 then we really cleaned and checked the head $85.00, next we resurfaced the head, $100, now we have replaced the guides and installed all new exhaust seats, $300. We then did the rest of the valve job for $150.00 So at present we have pulled the engine out, took it apart and did a once over on it. We have then completely did the head and we have spent $1445.00 (not including parts)
Next we move onto the block. To really clean that block will set you back $106.00, Around $75.00 to magnaflux it, Around $105.00 to resurface it (so many people do not do this and wonder why they can not get a good seal on the head) Next we are going to align hone the main journals. This is a step that many leave out but it insures that your crank is now running straight and true in your block and that all of the main journals are the correct size for the new bearings you plan on installing, $163.00. The boring and honing of your block will cost an additional $60.00. Now the block is finished so we have a finished block and finished head and we have spent $1954.00
Now let's finish the crank and rods; To check the rods and completely rebuild them including new small end bushings (but not the cost of new rod bolts) $167.00 To do the same to the crank will set you back $220.00 So now we are ready to move out of the machine shop and back into the engine rebuilding room and we have spent $2341.00 and we still not have paid for any parts!
Once we are back in the engine room every little part of the engine needs to be cleaned and checked. For us, we do not even look at rod, main or head bolts/studs. To check each of them in a stretch gauge would cost more than just replacing and at least we know where we stand. All soft parts, gaskets and seals go into the trash. So does the oil pump and water pump. If the vehicle has an oil cooler that is gone too. Just no way to know you really got all of the dirt out. Timing chains and tensioners go by the wayside too. Most times so do the timing gears. Run your thumb over them and see if they feel sharp or abrupt. Time to toss them. The cam needs to be checked closely for wear ( lets assume it looks good) If you see the slightest bit of wear on a tappet tossthem! Push rods are usually OK.
So we have cleaned all of the parts, chased threads on all of the studs being reused, cleaned and tapped bolt holes on everything else and now we are ready to put it together. First we wash it again to make sure we did not leave a little something behind after our machine work. Then we re-check the size of the bearings as we drop in the crank (we have had many issues where the crank is exactly where we want it but the bearings are not quite what we were expecting) Then we check the ring gap and file as needed to get correct clearance. You do your ring gaps on each ring for each cylinder. Now that we are happy everything is correctly sized and cleaned we actually put the engine back together. Next we tape it up and paint it the colors it is supposed to be. Now I have an engine that is ready to go back in the car. In our shop we do a few more things at this point. We rebuild the carbs, resurface the flywheel, replace the clutch, install new front and rear seals in the trans and rebuild the radiator (I will not warranty an engine if the radiator and cooling system are not done) But we were just talking about the engine here and we will assume you just had all of the other work done. So the engine room just added another $1800 to the job but all we have left is to drop it in the car and set it up another $600 and the car is setup and has 25 miles on it So you have just correctly taken your engine out of the car, rebuilt it correctly and re-installed it and it has cost you $4741.00 Now this is the labor and just about no parts and this is being built as a stock engine, no trick head work or custom pistons, variable timing or anything else.
Now onto parts. For this article I am going to use stone stock parts bought from Moss, $1900.00 and these are stone stock parts and where applicable "white box" I personally advise against using bottom line parts but would recommend that you upgrade where ever possible. I do not mean moving into custom forged pistons and hand made gaskets but AE pistons and Payen gaskets, uprated oil pump etc. but for this exercise we are staying with base parts. So when it is all done you have taken your 1969 MGB engine out of the car, rebuilt it and put it back in and it will cost you around $6641.00 and you still have not addressed you radiator, carbs, clutch, distributor, oil hoses, cooling hoses or any of the other things you should do when you do an engine. So if you called me for a quote for this job I would tell you $8800 but then I included an uprated radiator, installed electronic ignition with new vacuum advance, rebuilt carbs, new ignition wires, new oil lines, new coolant and radiator hoses, new clutch and resurfaced flywheel and I use uprated parts, better studs and bolts, water pump, oil pump, etc. So when you get a quote from someone find out what they are offering and why before you compare prices. Like I said way back at the beginning of this article the first thing you need to do is sit down with your rebuilder
But now you have an engine that with a little bit of care will out last you. It can run on any of the fuels being offered and you can use either a quality normal oil or better yet move up to a very good Synthetic.
I hope this article may help you understand why a truly and correctly rebuilt engine costs what it does and when you do compare one engine shop to another you know what to ask them about to see if shop A and shop B are truly offering the same engine