M30 rebuild

[Jay 535i]

Just for my own information, what tasks and costs are part of an M30 rebuild?

Does a rebuild essentially make the engine good as new?

[Scott H]

there are a lot of things you should look at, at a minimum. but you can do anything you want really.

Just for my own information, what tasks and costs are part of an M30 rebuild?

Does a rebuild essentially make the engine good as new?

[Kalevera]

Rebuild is a vague term.

A bottom end rebuild could consist of bearings/caps, or much more (boring/lining/you name it).

A top end rebuild is equally as vague. Sometimes you get away with just regrinding/polishing the valves and seats, others require new guides, the head needs to be decked (warped), cam may need grinding.

As long as nobody assed up your motor, it hasn't been overheated or RTVd to death; I can practically guarantee that it doesn't need anything at 135k...it's a relative baby to some of the others floating around. In fact, my spare motor has more mileage than yours does. People often make the mistake of thinking that classic BMW engineering is tantamount to something the big 3 would've produced in the past twenty years....but that's another topic, for another day.


best, whit

[Scott H]

Check compression and leakdown before taking it apart. I'd recondition the cylinder walls and check them for conicity and uniformity. Re-ring the pistons. No use putting together a bottom end if the rings aren't sealing for whatever reason. Also might as well replace the oil pump, timing sprockets and chains, and chain tensioner whild your in there.....

man...if you wanted to do it right, the list is long

A bottom end rebuild could consist of bearings/caps, or much more (boring/lining/you name it).

[Jay 535i]

Thanks guys.

What kind of costs are involved? Give me a range.

My engine certainly doesn't need any kind of rebuild at the moment, but I am thinking ahead to the future and a possible turbo kit.

I know a compression test is the first thing the turbo kit calls for, but I want to plan for the worst and assume my engine will need some work. TCD claims a high-mileage engine with good compression is perfectly suitable for their kits, but I don't know if that's optimistic. In any case, I want to know just how many pennies I have to save to have a reliable blown M30.

[Scott H]

Depending on what you find for machinists in your area and how much you decide to replace, as well as how much work you decide to do yourself, I'd say you are looking at between $1,500 and $3,000

Here is my breakdown for my project. I took out as many items related to the swap as possible (e.g. tranny stuff, a/c stuff, etc etc):

Head rebuild which included tear down, cleaning, new guides, new seals, spark plug thread chasing, one new intake valve, a minor resurfacing, and extraction of a handful of snapped manifold studs (I'm putting it back together) $450

Dipping of block and intake $200

Rings, bearings, camshaft, rocker arms, oil pump, new chains, new sprockets, gasket sets for upper and lower, all new hardware $1,500

What kind of costs are involved? Give me a range.

[Jay 535i]

Depending on what you find for machinists in your area and how much you decide to replace, as well as how much work you decide to do yourself, I'd say you are looking at between $1,500 and $3,000

Here is my breakdown for my project. I took out as many items related to the swap as possible (e.g. tranny stuff, a/c stuff, etc etc):

Head rebuild which included tear down, cleaning, new guides, new seals, spark plug thread chasing, one new intake valve, a minor resurfacing, and extraction of a handful of snapped manifold studs (I'm putting it back together) $450

Dipping of block and intake $200

Rings, bearings, camshaft, rocker arms, oil pump, new chains, new sprockets, gasket sets for upper and lower, all new hardware $1,500

Cheers. That's about what I figured.

Isn't $3k approaching the cost of a whole freshly-rebuilt M30?

Ultimately, I'd like to achieve a RELIABLE 400 RWHP. This car must remain usable as a daily driver. I'm trying to determine roughly what that would cost. I think between 10k and 15k, Canadian, all in. If it's nearer 15, then it'll be a hard decision whether to go ahead with it or instead leave it alone and buy a late model RX-7 for when I'm feeling sporty.

Any suggestions or input are appreciated.

[Dave M]

Cheers. That's about what I figured.

Isn't $3k approaching the cost of a whole freshly-rebuilt M30?

$4000 for a rebuild M30 from Bavarian (I believe an expensive source).

I'm rebuilding the M50 at the moment and started by purchasing a used, rebuilt block (main/rod bearings, rings). My choice to have someone else do the bottom end rebuild was based on my location (Thunder Bay=no bmws) and hesitance to purchase the necessary tools. The block, rebuild and shipping was @$1100 Can. total. My head was recently rebuilt so I won't do much unless inspection warrants it. You must consider the 'while you're in there' factor as well. Maybe a few hundred for a clutch kit (you want forced air don't you ), plenty of gaskets and engine seals, maybe a lighter flywheel, shift linkage components if an old manual tranny is swapped. $hit, you can count on $100 in fluids. The list can go on.

The key is DIY. I will be able to swap a 'new block' cheaper than it cost me to just have my head rebuilt. Plus, I can spend some evenings in the garage, with my friend beer.

I'm over my head, but as long as you guys are around, it should run again.

Dave M

[Jay 535i]

$4000 for a rebuild M30 from Bavarian (I believe an expensive source).

I'm rebuilding the M50 at the moment and started by purchasing a used, rebuilt block (main/rod bearings, rings). My choice to have someone else do the bottom end rebuild was based on my location (Thunder Bay=no bmws) and hesitance to purchase the necessary tools. The block, rebuild and shipping was @$1100 Can. total. My head was recently rebuilt so I won't do much unless inspection warrants it. You must consider the 'while you're in there' factor as well. Maybe a few hundred for a clutch kit (you want forced air don't you ), plenty of gaskets and engine seals, maybe a lighter flywheel, shift linkage components if an old manual tranny is swapped. $hit, you can count on $100 in fluids. The list can go on.

The key is DIY. I will be able to swap a 'new block' cheaper than it cost me to just have my head rebuilt. Plus, I can spend some evenings in the garage, with my friend beer.

I'm over my head, but as long as you guys are around, it should run again.

Dave M

Thanks Dave. I had hoped that my $10-15k estimate included the 'while you're in there' stuff, as well as a transmission swap, performance clutch, LSD, etc. I hope that's not naive.

I intend to have Bruno do the work for me, which will cost money, but much less than a big fancy shop. I simply cannot do this work myself.

I want to do this RIGHT, but at the same time I'm aiming for value. There's no point IMHO building a 400RWHP monster if things on it are breaking every week. At the same time, it doesn't make sense to spend more than $15k on this car because for that money I could buy a fast sports car (e.g. RX-7, 300ZX, 944 Turbo) and have TWO great cars.

I'm still not sure though if I should be considering buying a new engine or rebuilding mine. I guess a thorough inspection will make that decision easier. Those Bavarian rebuilt engines are pretty appealing, and my existing engine ought to be worth something to somebody.

If I do decide to buy a rebuilt engine, is the M30 still the one to have to reach my goal of a reliable, reasonably-priced 400RWHP?

Keep the input coming. I appreciate it.

[bahnstormer]

why not buy a metric mechanic motor for 6 grand? 280hp?
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