Blew the rear main oil seal! [Engine Overhaul]

[timsrv]

Here's a thread where this is discussed: http://www.toyotavantech.com/forum/s...have-any-input

I know there's more, but don't have time to search right now. Good luck. Tim

[Canoed_son]

Tim-

I am having my 3Y rebuilt by Brian at M&B Cylinder Head in Portland, OR. So far he's done a bang up job! The head is all ready to go, but its time to order parts for the block and I am wondering what needs to be replaced/what I can reuse. Obviously rings, washers, plugs are going to need replacing. What about the rods/pistons though? He says he bored out the cylinders @ 20 (0.5 oversize). Also, it wasn't clear from reading this thread whether or not its possible to reuse main/rod bearings. I'd like to be able to reuse those if at all possible since trying to find OEM has proven to be frustrating...they list them as MARK 1-3 for mains and MARK 6-8 for rods...are you familiar with these designations? Do they indicate different sizes? Trying to order as much OEM as possible and the bill is already racking up let me know what you think!

Cheers,
Pete

[Burntboot]

Where I come from, blocks aren't bored until the new pistons are on hand so that all can be properly matched together.
And the rings also have to be properly sized as well.

If the crank and rod bearings were marked as to where they came from and assessed with plastigauged and found to be within spec,
then reusing them is fine, as long as there aren't any marks or grooves.
Back in the day, we reused factory bearings all the time as we often had better clearances than with replacement A/M bearings.

[timsrv]

I have associated with and spent a lot of time in machine shops when I was younger, but haven't been keeping-up with current practices over the last 20 years or so, so it's possible (maybe even likely) that practices have changed............so take what I say with a grain of salt. Also, with today's machines and manufacturing techniques, the specs on quality internal engine parts have become consistently "dead-on". So perhaps your machinist is well within his job description to do it that way, but way back when I was involved, standard practice was to 1st have the new pistons assigned to each to a cylinder, then each cylinder was bored to precisely fit it's piston. So to me, not 1st having pistons just seems wrong.

Any time you put new rings in an engine, they should be checked and verified that the gaps are not too small. Gaps that are too big will allow small compression leaks, but that is far better than small gaps. Gaps that are too small may not allow for heat expansion and that can result in broken ring lands on the pistons, so follow the specs in the Toyota manual. FYI, Toyota changed the ring gap specs to be larger in the later years of van production, so it might not be a bad idea to go for the specs found in the 89 service manual. If you check my blogs you will find a whole section devoted to piston rings where I measure and discuss different brands of rings. Based on what I learned there, I would recommend genuine Toyota rings.

Every engine I've rebuilt or overhauled so far I've replaced the bearings. Never before have I paid attention to mark 1, 2, or 3. I just measured the crank to insure it was in spec, then got aftermarket bearings. I've had to have cranks machined undersize before, but rarely for a Toyota. In those cases I just purchased the bearings for the new size and everything was good. That's always worked out okay for me, but I've never been completely satisfied with clearances. They've always come out very close, but seems there's always at least one or 2 journals that are a tiny bit off (barely within spec or perhaps just a tiny bit outside on the "loose" side of the spec). I've never had a serious issue as a result, but I have encountered slightly low oil pressures and I blamed that on the slightly loose bearings.

I'm currently gearing up for another 4y engine rebuild, and this time I decided to use genuine Toyota bearings. This engine has never been torn down, so not knowing what bearings are in it (which mark), I ordered all possible combinations from Toyota. When I get things torn down I will be checking and replacing with precisely the same bearings Toyota originally used (it will make me feel better ).

I don't remember how much $$$ they were (purchased almost a year ago), but they were a bit expensive. I purchased most from www.toyotapartsdeal.com, but they claimed some were NLA. I ordered the "NLA" ones from another on-line Toyota parts store (slightly more expensive) and was successful.

Not sure if I'll take pics and/or document this new project because I've already done that (here and in my blogs), but I may edit and/or add to things as I see fit. Good luck with your project. Tim

[Lois85]

This is a really great thread. I love all of your photos! I am hoping that this wont happen to me.. is there a way to prevent the rear main oil seal to not blow? What are the signs that you should be checking for? My van just started having a little bit of a hard time changing gears... seems like it takes a little too long and when i lay off the gas is when it finally goes. any suggestions?

[timsrv]

Having the main seal blow is rare. It only happened to me because I was running a thicker oil and was pushing it hard on a cold day. Not likely you'll ever have this happen to you. Here's a few threads for your review regarding transmission shifting issues:

http://www.toyotavantech.com/forum/s...months-sitting

https://www.toyotavantech.com/forum/...ble-adjustment

https://www.toyotavantech.com/forum/...erdrive-issues

[MyToy]

Could not find anything on the site on what I need for the rear main seal.
Just had my engine over hauled and the rear main seal is leaking. Can it be replaced from the outside or does the engine and crank have to come out again

MT

[djshimon]

You can drop the tranny to access the rear main seal without moving the engine.

[JDM VANMAN]

I took the van in last year to have the rear main seal replace and did the clutch while the transmission was out-













JDM

[Dr.Roob]

Worst case scenario is that when your engine was overhauled (assuming the bottom end was done), the Flywheel wasn't tightened sufficiently which results in it developing a wobble and screwing up the seal (and potentially the crankshaft face at the Flywheel end.
Good luck - doc

[Jan-Willem]

I just installed a ‘cloyes’ timing kit from rockauto, it fits perfectly. I see no difference to the (toyota?) one that was on there, except the timing location dimple and chain. Type of steel and the machining look identical. Unless the previous owner installed the same cloyes kit, but i doubt it, as the chain was stretched considerably, so I assume it was original.
CLOYES 94057S