I have an 88 auto corvette that has a few problems. The engine knocks at idle only in park, the transmission has always hesitated to upshift (either requires me to let off the gas or give it more before it will shift) and recently started slipping when going from 2nd to 3rd, and finally, I have a cabin vibration at around 20-40 mph.

The reason I bring all three of these issues to the table is because I plan on fixing them all as one big project. Since a rebuilt would require me to disconnect the trans, i might as well rebuild the trans or replace it while I have it out. And since i need to disconnect the driveshaft anyway, i might as well replace the u-joints. Before i get into this further, i want yall to know that ive never done an engine rebuild before or replaced a transmission.

Engine- After having a retired mechanic friend of mine check out the noise, he is certain a bottom end rebuild is necessary because the noise seems to be coming from deep within the engine around the crank. Not to mention, my oil pressure drops very low (can even dip into red for a split second) when oil temp is above 200°F and my idle is at 600rpm. But when my idle is at 700rpm (thanks to a tune chip) my oil pressure is fine. I am running 5w-40 now with same issue. For the bottom end rebuild i want to do it with the engine in the car (if at all possible)

Transmission- like i said, ever since I've had the car, its never liked to upshift and can be very awkward to drive. I could go into greater detail on the intricacies of how I handle driving with this transmission, but i dont think it will help much. Ive done much research on the tv cable and the governor and they are both fine and adjusted correctly. And the newly acquired slipping from 2nd to 3rd only proves im in need of a rebuild or replacement. Ive gotten quotes for both. $600 for a rebuild with a warranty, or $600 for a replacement with a warranty. A warranty is a must for me. Ill be taking out and installing myself

Vibration- i believe it could be my driveshaft u joints causing the vibration. I just recently replaced my half shaft u joints and they were horrible. Plus it couldnt hurt to do cheap maintenance while im there even if it doesn't fix the problem.

Main Questions-

• what engine rebuild kit should i buy for my stock L98
• , will i be able to do a bottom end rebuild without having to lift or remove the engine,
• are there any major obstacles or things i should take into account,
• should i replace or rebuild my transmission,
• What special tools should i buy or rent if any
• Any informational videos you recommend
• Any tips or past experiences
• What u joints should i get from my autozone or oreillys (they usually dont have spicer but i dont care about the brand)
• If i had every day off and only dedicated my time to doing all of this, how long do you think it should take me

To me it all seems like a walk in the park except for the bottom end rebuild. Im a little anxious on that part. Thanks

 

How are you going to machine theblock with it in the car?
Maabco has shortblocks for 1000

 

Rebuild in the car is more about desperation than long term reliability. Some call it the big band-aid between rounds. If you're going to do it, once you drop out trans there not alot to pull engine. You won't know what you have until it's apart. You could go with a crate motor , reman short or long block. And then....there's the LS crowd who.say ideal time to swap a LS and a 4l60e from a Fbody, pick up, or. Holden. Lots to ponder.

 

As much as id love to drop an ls in this thing right now, im really just looking for short term reliability. Maybe about 5 years. I just dont have the time, money or knowledge to do a whole swap just yet. I plan on keeping this car for the rest of my life and its my daily for the moment so im expecting it to fail on me in the future. I just need to squeeze a few more years out of it to give myself time to get comfortable before i do any ambitious building.

 

I know machining the block would be ideal, but im just talking about replacing bearings, seals, and gaskets from the crank down. That's all i have the money for. Trust me, I'd love to do more

 

Well...you'll need a crank, so you might as well get a stroker crank, for virtually the same money. IMO.

 

Which one would you recommend and would that require a tune?

 

you cannot effectively rebuild an engine in the car period, sure i have put like 1 rod bearing in before by just pulling the pan off but that is sketchy.. to say the least. the vibration is likely the result of a combination of bad engine/transmission. to me it sounds like you should focus on the transmission first and pull it out, take it to a shop get it rebuilt and see where you are at from there, depending on you'r financial situation. if the wallet is good with an engine and transmission rebuild all at once, sounds like you need it. i would opt for rebuilding what you have just because the numbers match the car, for what that's worth. those L98 engines are pretty much already built with all the "good" stuff that people from the 80's wanted to have to make pretty good power.so maybe just tear it down and refurbish with rings and bearings and you will be good to go if you just want to have a good strong running car again. i mean you can build the snot out of it but there will always be someone faster.

 

Cheapest one that you can find, if you're doing an "in frame".

 

Its not that hard to pull the pan and check bearings with plastigauge.
How to Check for Bad Main Bearings (itstillruns.com)

 

You can get a Scat cast rotating assy pretty reasonable no need for forged cranks top line pistons etc
TPIs dont turn fast enough to need that. Get some better heads/intake when money allows. Yes youll need a tune but for 200?? PCM for less, Wongs performance can get you an updated chip.
Cube # doesnt sound like a huge difference but believe me the toruqe...its like having a big block. You can get a cam cheap say from Elgin.
Ask questions and be resourceful
Sounds like for now a stock replacement crank rings bearings, a backyard hone is where youre headed
If the trans is out you only got 2 motor mount bolts holding the engine is.
If you were closer Id give you an engine stand, so much easier working on a block. Youll wanna put new freeze plugs in anyways.
Lost one and sold the car over it too much of a pain to do with it in car

 

If we're talking about pistons, then we're talking about yanking it all out to get honed/machined. If it makes you feel better, when the 396 in the MCSS developed a rod knock, yanked the engine out, flipped it over on an engine stand, polished the journals with 400, replaced rods bearings and checked clearances with platigauge. Oh also replaced the already brass freeze plugs (probably didn't hafta) behind the flywheel. Put on about another 20k miles on that engine over a 5 year period with no issues.

 

Before you start taking things apart take a look at your torque converter. The mounting bolts may have came loose. That can cause the knock in park and also give you a vibration.

 

Earlier this year, I fixed a timing issue that freed up some ponies and almost immediately heard rattling from the rear of the engine. Took off the torque converter shield to find that one of the 3 bolts had broken off and was rattling, another one was just gone, and the last one was the only one bolted in. I replaced the bolts and torqued them to spec, so i don't think its that, but ill check when I take the oil pan off

 

What's your hot idle oil pressure? If you do have a bearing issue the cheapest path would be a reground crank kit for ~$250 from a local auto parts store. It would come with bearings and take your old crank as a core. Of course doing that work with the engine in the car and not cleaning and resealing everything is crazy. It will be more work and more likely to end badly than pulling the engine and doing it right (as others have said). Good luck either way!

 

Considering what the op said about converter bolts, doesnt a crack in the flexplate make some odd noises?
Anyhoo...all the bottom end work was done when mechanic friend identified rod knock. Heard the unfamiliar sound but never knew what it was.

 

Thanks for that info on the flex plate. My plan is to check everything out under there before i go any further.

 

If the trans is off and you want to do an in car rebuild, just pull off as much as you can and pull the motor.

It’s only two bolts for the motor. Leave the rad and condenser. Pull the hood. Done deal. Everything else would come off just getting the heads off.

I honed and replaced 8 pistons with the motor in the car. Trans still hooked up. It sucked. Motor was out two months later to do it right.

 

Yes a cracked flexplate can make some weird noises too. With the converter bolts previously broken and missing it should be checked out.

 

If it turns out that the knocking is coming from bad bearings, Im just trying to replace bearings, crank, seals or anything else accessible from taking the oil pan off. Hence why i called it a bottom end rebuild. My pistons and everything else above the crank should be fine. Im not looking to do any sort of machine work unless i have a reason to. I also have zero equipment to take out the engine even if i wanted to. Thanks for the tips on taking the engine out though and thanks for sharing your past experience.