That rod bearing with the copper showing is certainly worn out, but since it has not spun nor show signs of scoring, the crank should be Ok.
I have replaced con rod and main bearings in an engine without pulling the crank in the past. As long as the crank pins are not scored we can just install new, standard size bearings. A full set is ~$50-$60. We need a new pan gasket also.
Would replacing crankshaft bearings require pulling the transmission?
Having never done it on a KA24DE specifically, in general, no.
Pull the cap, rotate the bearing out of the saddle, rotate the new one in, swap the bearing half on the cap, torque it back in.
From the photos, it looks like this should work.
It depends on the style of main bearing.
My bet is yes, you’ll have to remove the Trans and the chain.
Many (not all) main bearings have one or more one piece bearing that slide over the end or snout at one end or the other.
Plus the front and rear crank seals are usually replaced at the same time…but again depends on the style of rear crank seal…
Do you have a time you’re going to do this? I’m interested in watching this sort of heart surgery.
I don’t think there was enough wear to justify replacing the main bearings - but that is just my view.
rod bearing - yes, no question, but they were not terrible.
We are still debating if it would be worth pulling engine out entirely (would get block decked/honed at machine shop) or only replacing rod bearings. Would be more educational to rebuild bottom end but probably cost ~500 for new pistons, bearings, gaskets, machine shop work, etc.
No meeting today (14th), next week (21st) we will be pulling the engine / trans out of the car and then planning out how best to rebuild the bottom end. Removing the JB welded on flywheel will be interesting.
If you decide to do the main and rod bearings, keep in mind that Nissan KA engines have concentric bearings and the parts should only be purchased from Nissan, as aftermarket replacements will usually come all as one size. Each of the bearing journals on a KA is a slightly different size, and corresponds to a set of numbers etched into the block. The same is true of the crank pins. The alternative is to have the crankshaft and block align honed so all bearing surfaces are the same dimensions.
At that price, it may be more cost effective to just buy a running spare motor. KA24DEs are cheap and available.
Thanks, yeah I watched the following video, the different grades (sizes) of bearings from nissan vary by very small amounts, some forum posts say the differences are within tolerances even if you get standard sizes, we will use plastigauge to double check everything
I would caution that my own KA spun a bearing and seized as a result of a technician failing to recognize the bearing size issue when he rebuilt it. I strongly recommend consulting a machine shop prior to ordering any main bearings for a KA.
There is an outstanding machine shop in Garland called “Day custom engines” may also be listed as “republic custom engines”
Great service.
It took 1 hour 56 minutes without too much rushing to get the engine out.
With some heat and the newer Ryobi impact the jb welded on flywheel didn’t take too long to get off
Quick question – what was the very last thing that happened to the engine right before the knocking started? Was it the running it with low/no coolant? Or was it something else?
This engine lost its flywheel in the practice for the first race, because the past owner removed it and did not use new bolts when he reinstalled it. Only five of the six bolts could be installed at the time (working in the dirt at the track), which is why it has JB Weld holding it also.
The big question is whether there was any indication of movement between the crankshaft and the flywheel? Could movement there be the source of the odd noise?
It blew head gasket and was run to only steam in engine, unknown temp, then when fixing head gasket I messed up upper timing chain reinstall by a tooth, then we ran it on race track with the incorrect timing (not sure if ignition was happening before or after when it should).
Seems unlikely, it was on there very solidly, had to hammer it off with a pickle fork after removing all the bolts.
So I guess at a minimum, some thread repair on the crank is needed for that flywheel bolt? Maybe drill the bolt body out, then chase the threads, hopefully removing the last bits of the bolt? And then new bolts.
Don’t forget that it is an aluminum head on cast-iron block, so different expansion rates. I’d trust the block before the head. It’s also likely the head warped off the block enough to allow fluid transfers, vent some of the water into the oil, thinning the oil, and letting the conn rod bearings contact. I’d guess take the head to a machinist and see how warped it is and replace bearings. Depending on miles/hours of use, consider the mains and rings? Also check straightness of conn rods as when they contact the crank they like to get twisted since there’s a bunch of rotation going on at the rods.
Personally I’ve only had a warped head repaired and after putting my B230FT all back together I’d wished I’d replaced all the other wear items, but that’s on a daily driver.
Given that description of events, I would strongly consider replacing the motor entirely. The head is likely trashed if it was run on track duty with a blown head gasket, and the block and crank likely aren’t faring well enough to justify machining and a new head. Not at what a KA costs on the open market.
That said, if you do opt to replace the engine outright, be sure you only use one from another 240. The FWD and truck versions are very different and not as stout.
