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.
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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.
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There is an outstanding machine shop in Garland called āDay custom enginesā may also be listed as ārepublic custom enginesā
Great service.
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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 didnāt take too long to get off
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Quick question ā 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.
Donāt forget that it is an aluminum head on cast-iron block, so different expansion rates. Iād trust the block before the head. Itās 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. Iād 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 thereās a bunch of rotation going on at the rods.
Personally Iāve only had a warped head repaired and after putting my B230FT all back together Iād wished Iād replaced all the other wear items, but thatās on a daily driver.
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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 arenāt 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.
Will begin tearing down engine tonight (in an organized and orderly fashion) if anyone wants to assist
We got the engine mostly apart except for the bottom end,
Found an interesting thing that resulted from when I messed up the timing chain reinstall (described in first post in this thread)
The intake valves had impacted the top of the pistons, I looked as close as I could at the valves but could not see a mark or obvious damage to any of them.
Will be taking the rest of the bottom end apart next week.
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I canāt tell if itās the picture or an illusion, but the rear most two cylinders look like they were hitting the head. If thatās the case then thereās your knocking.
Yeah, intake cam was off a tooth on the secondary chain, thatād do it. KA valves are pretty stout, this isnāt the first Iāve heard of this exact scenario. Iād check clearances between valve and seat just to be on the safe side, but you may not need to do anything to the head.
Now would be a good time to eliminate some of the excess nonsense, like the overly complicated PCV system. And the secondary timing chain guide. That thingās just a liability.
@Brandon_Green The timing chain was recently re-aligned properly but the conn rod noise was still there, right?
A good tutorial for what we will be doing thursday