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My first complete engine rebuild... B230FK, 300bhp goal


Aug 18, 2015
Welcome to my first complete engine rebuild! Do I know what I’m doing? I'd like to think so, but possibly not really. I have read a lot of Turbobricks threads and watched the overboost racing videos on youtube about how to build a B230 bottom end as a start, but I’m very much open to comments. I’ve replaced head gaskets before, but this is the first time I’ve completely stripped an engine down to the block.

The engine currently in my car (1988 240, I engine swapped it in 2015) is an increasingly tired B230FK from a 1997 940 with a 19t, about 20psi of boost and 40% leakage showing after a recent leakdown test. It’s also got an issue with a coolant leak down the inlet manifold side of the block after a swap to a maxxecu, so I’ve an ongoing question about whether I have too much timing advance. I asked about that issue in a different thread, I’ll need to revisit that before putting this engine in the car.

Anyway, back to this engine – after the leakdown test it was time to look at options for an engine rebuild. Unfortunately I’m a bit constrained on space to work on bigger projects on the car as I live in London and the car is in a communal underground carpark, so finding a replacement engine or just a bottom end and rebuilding that somewhere else, then swapping it into the car at some point in the future was going to be easier. After a couple of false starts I found an ebay listing for a B230FK from a 1997 940 that was being broken due to crash damage, with only 65k on the clock. The engine was a bit more expensive than the other engines I’d found, but I figured it was worth the extra for a low mileage engine as it most likely wouldn’t need a rebore – and new pistons are expensive. So I bought it.

I got the engine delivered to a local garage that I’ve used for various things (including renting a lift on a Saturday occasionally), then stripped it down completely. The low mileage appears to be genuine, as everything was in great shape inside: honing marks visible in all cylinders, waterpump spins freely, oil pump the same and the bearing surfaces were all in good shape with no visible wear or missing coating.

I took the bare block, crank and head to the local machine shop for the following:

Head – replace inlet stem seals, lap valves, skim

Block – deck the top surface, check the bores and advise- they measured within spec and the bores were lightly honed

Crank – polish bearing surfaces.

When I picked it up, the main bearings were in a box having been removed before dunking the block in their hot tank.

So now I had a block ready for a rebuild, but first – paint. After watching a load of videos of people prepping blocks with a wire brush attachment on a drill which didn’t look like much fun, I gave a local soda blasting place a call – they quoted £100 to clean the block and all the loose engine parts, which sounded like a bargain to me, so I delivered the lot and picked them up a week or so later.

The block is now completely clean both inside and out, they blasted through all the oil galleries as well. Unfortunately between the machine shop dunking the block and the soda blasting place blasting it, the surface of the intermediate bearings now look and feel like a gravel driveway, so those will have to be replaced (VP autoparts has a set that do not need to be linebored after installation, I understand the original Volvo ones require boring) so I haven’t got any further with painting, since the block might have to go back to the machine shop to have those bearings installed. I did clean the block completely using degreaser and a scrubbing brush and wow, now I know why it’s called flash rust – little specks of orange appeared almost immediately. I’ve sprayed down the whole block in WD40 (that’s all I had to hand) to protect it for now. The soda blasting place also cleaned the pistons, and removed all traces of carbon from them, including in the ringlands.

Annoyingly, one piston appears to have been dropped at the soda blasting place, but the damage is minor and I think it’s usable after dressing down the top to make is flat to avoid any hotspots?

Poor surface on the Intermediate bearings



Flash rust after degreasing


Flash rust in the bores


I’m not planning to change the head or turbo initially, but I do have first refusal on an extensively machined 531 head with bigger valves from a friend’s abandoned project, so I’ll be doing a bit of future proofing to the bottom end so I don’t have to revisit it later. With that in mind I’m currently planning to rebuild the bottom end with:

Standard Volvo main bearings

Standard Volvo big end rod bearings

Maxspeeding Rods

Existing standard Pistons with new Volvo Rings

ARP Main Bolts/studs

ARP Head studs (not sure I need these for this power level – 300bhpish?)

Intermediate shaft bearings from VP

Zeligsgarage.com oil transfer tube

Volvo gaskets and seals

IPD oil pump reinforcement ring.

I’m in no rush to complete the rebuild, as the engine currently in the car is still working. A few initial questions:

ARP head studs? Do I need them?

The 350bhp budget thread refers to cleaning up the oil return channels… I’ll ask there as well, but I’m not quite sure what that means.

What else should I do /have I missed?

Too late to just throw a set of rods in it...oh well. Fun project to learn how this stuff works!

Someone else can comment on that piston...I don't know. Also, the effects of "soda blasting" on those pistons, I have no idea if that's a concern around the ring grooves.

Confirm best method for cleaning out the oil passages thoroughly before assembly. I've not done it personally, but it's necessary I think. At the front of the block under the water pump there should be a plug (possibly removed by machine shop?) that is a tapered pipe thread. That, plus the one at the other end, inside the bell housing, would give access to run a brush through the passage and flush it out. Being a tapered thread, you do not tighten them like a bolt. You need to use a thread sealer, and snug them "wrist tight". Overtightening it risks cracking the block, so just be careful.

The deck of the block should have had two hollow alignment dowels to align the head when it goes on. Make sure those are in place when the head goes on. If you didn't remove them, machine shop must have in order to deck the block surface.

Did you note the bore letter for each hole before the block was decked? I see a 'C' size piston there...others will have letters, likely different letters, so hopefully you have a way to put #1 piston back into #1 hole, and so forth. Could probably measure the bores, too....

That's all I can think of right now as an engine-build-observer.
Yeah, I did consider just throwing rods in and calling it done, but then I decided to have the bores checked by the machine shop and put at least new rings in it, and then it made sense to have the block decked whilst it was apart and the crank polished… so it’s snowballed a bit. Definitely enjoying the process though.

I marked the pistons on the underside using a centre punch, so they’ll go back in the same bores they came from. I know about the C/D markings to show the original bore size.

Soda blasting should have only removed the oil and carbon and not touched the aluminium of the piston, I’ll measure the piston ring axial clearance in the ring grooves with new rings and see… and report back what I find.

Noted on the pipe fittings in the oil gallery ends, I can certainly remove those and clean through.

The head locating dowels were removed by the machine shop for decking and then replaced afterwards.

That piston would worry me, if you're going to the trouble and expense of doing this you might as well try and find a new one, I got a set of Mahle pistons years ago. I believe they were the original maunfacturer for volvo but dont quote me.
I would have hot tanked it after blasting not before... if it's going back for bearings I'd open up those oil galleys and have them wash it again.
That piston would worry me, if you're going to the trouble and expense of doing this you might as well try and find a new one, I got a set of Mahle pistons years ago. I believe they were the original maunfacturer for volvo but dont quote me.
I can buy a new standard piston for about £60, perhaps I’ll just replace that one - I’ll carefully check all the others for damage before ordering
Those EBAY leakdown testers are not legit. They use the wrong orifice size and pressure. You do not have 40% leakage. I know this because I bought one, disassembled it, and modified it to meet the correct FAA standard by drilling out the existing orifice and hammering in a brass insert with the correct orifice. I also replaced the "leakdown" gauge with a 0-100PSI gauge.

The spec for leakdown tester is a 1mm orifice of 6mm length with a 45 degree exit. The orifice on these EBay pieces is 2-2.5mm. The spec pressure is 100 PSI, the EBay ones use 40 PSI if I recall correctly.

My car was showing leakdown readings of 40-50% before I adjusted the device and 10% after. It's still not "amazing" but it's certainly not "replace the engine" especially considering it's from the 70s.
Fair call on the eBay leakdown tester not being all that accurate… but I’m pretty committed to the new engine build now, so onwards!

Update: I’ve ordered one new piston, new intermediate bearings from vp volvo parts in Sweden (that don’t need line boring after installation) new bearings, h-beam rods, arp main bolts and head studs as well as a lot of gaskets and seals etc.

So once the intermediate bearings arrive I’ll take the block back to the machine shop to have them installed. After that, paint! And then the actual rebuild can begin…
How are you getting on? I'm building a similar engine at the moment. Mostly standard, just put together with care.
This is a good opportunity to replace the core plugs. Even on a low mileage engine, they will have their fair share of corrosion by now and I've had a few spring a leak. It's a major pain to replace them in the car and easy now.
ARP head studs instead of bolts probably aren't necessary, but if you have them....

Too late now, but for what it's worth I think that piston would have been fine. That part does not touch the bore, so is not critical.
I also wouldn't bother blasting internal engine parts. All you do is make them cosmetically pretty, only to be hidden away again, plus you are adding wear, which you really don't want with used parts.
Make sure you get every last bit of blasting material out of the engine, especially the oil galleries as towerymt says. All it takes is a tiny speck to ruin a bearing.
Yeah I dithered a bit on ordering a new piston, then I decided I didn’t want to worry about it failing/causing a hot spot and bought a replacement.
Having the block fully soda blasted isn’t something I’ll do again I expect- the knock on result of having to replace the intermittent shaft bearings and the need to paint everything (like the area inside the bellhousing that was fine as it was) has meant it probably wasn’t the best approach… but I’m enjoying the process, so not all bad. The block has been cleaned and cleaned again, at least soda is water soluble and easy to remove, compared to if it had been sandblasted. The core plugs are in great condition so I’m going to leave them- hopefully I won’t regret that decision.

Otherwise I’m just waiting for parts to arrive- the new piston, h beam rods, main and conrod bearings, block vent adapter and a few other bits have arrived. The order from VP in Sweden is taking a bit longer, as soon as that’s arrived I can take the block back to the machine shop to have the new intermediate bearings installed and then paint it when I get it back from them.

Unfortunately painting it is going to be a challenge given the weather… I might have to wait for one of those random warm and dry winter days or else I fear the paint is all just going to fall off after a couple of heat cycles.

Do you have a project thread for your car/engine?