Mk3 MR2 Piston Ring Change Without Removing Engine - Toyota Nation Forum : Toyota Car and Truck Forums
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#1 Old 07-15-2012, 01:09 PM
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Mk3 MR2 Piston Ring Change Without Removing Engine

So my 2001 MR2 Roadster 1.8 vvti was burning oil, both at high revs and on the overrun. I've read as much as I could on various forums to determine whether I could remove the head and sump (and hence get the pistons out) without taking the engine out of the car. I have limited equipment just the usual garage stuff, sockets, screwdrivers, lump hammer but don't have any special lifting equipment therefore dropping the engine was a non starter.

There's not much on the forums about dismantling the engine whilst in situ but plenty of "experts" on the causes of the oil burning (oval bores anyone?), seems most people are posting based on other forum's posts or word of mouth? but nobody had actually done the job with the engine still attached to its mounts.

Anyway, I did a bit of backgrounding, plenty of time spent under the car and inside the bonnet just seeing if it looked possible to do the job and I eventually decided to take the plunge and give it a go.

The main issue I could see with getting the head off is the fact that you have to remove the timing chain cover before you can remove the head and there's not much room between the RHS of the engine and the bulk head. I had a look at the manual and it seemed to indicate that you can remove the cover with the engine still in the car so...I had nothing else to do this weekend!

Well I have to report it is entirely possible and I have pictures to prove the fact.
http://s302.photobucket.com/albums/n...ston_Ring_Job/

I can report that the cause for the burning oil on my particular engine is sticking oil control rings, this can be clearly seen in the pictures where the compression rings are nice and loose and springy yet the oil rings are gummed in and not at all springy resulting in oil migrating up past the control ring and into the combustion chamber. All 4 pistons have an identical failure mechanism, with the oil control rings not in proper contact with the cylinder bore.

It does seem to confirm that the design of oil control ring is not as good as it should be. There is no real wear on the bores (may not be to Toyota's exacting standards but that doesn't mean they are beyond further use), the cross hatching is still just about visible, the pistons do rock slightly but no worse than most other engines I've stripped (quite a lot) with similar mileage (87000).

I haven't put the new rings in and run the engine so can't confirm that this will fix the problem but I am totally confident that it will and I'll give an update once the car's up and running (should be sorted next weekend at the earliest).

I haven't posted this to enter into a discussion about why the engine uses oil, this post is merely to let people know that you can do the job without removing the lump and with only the most basic of tools (although I did have to purchase an M12 splined tool to remove the head bolts).

I might add a procedure if there's enough interest.

Ganzee
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#2 Old 07-15-2012, 01:16 PM
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The new oil rings should do the trick.
It was confirmed that the 1zzfe engine in the Spyder and Corolla suffered excessive oil consumption from the oil ring problem.
I have pulled a piston from my 3sgte without removing the engine. Honed the cylinder too.
Good work.
Let us know if it solves the problem.
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#3 Old 07-21-2012, 02:20 PM
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UK Job Done

The engine's been rebuilt, new gaskets, water pump, oil, filter, idler pulley bearing (good job I've got a lathe!), crankshaft oil seal, head bolts, valve stem oil seals, everything that need replacing has been done.
It runs as sweet as a nut, no smoke, quiet (apart from the rattly exhaust shield - must get that sorted), pulls great, smooth as silk and as far as I can tell no leaks!

All in all, a good two weekend's work but nothing too taxing. Took a while to figure out the best sequence to put the serpentine belt, tensioner and engine mount in place but got there in the end. It didn't help that one of the engine mount bolts picked up in the aluminium of the cylinder head but chopping 10 mm off the end of the thread fixed that (the bolts are extremely long anyway so no harm will be done.

Also, the workshop manual doesn't really explain the valve timing that well, it mentions dot marks on the inlet cam sprocket that don't exist but what it really means is the marks on the vvti mechanism (there is one mark and this should align with the similar mark on the exhaust cam, the pictures show this), the exhaust cam sprocket has the marks according to the manual. Anyway, removing the camchain and aligning the coloured chain links and the marks on the cam sprockets worked out really well.
It also helps to understand where the camshafts should sit when the crankshaft is at TDC; number 1 cylinder cams should point in towards each other and slightly above horizontal, the pictures show it better than words ever could.
Only been around the block a couple of times to bed things in but it's looking pretty good so far.

Anyone want to buy an MR2? I need a cheap car (to insure) for my daughter to learn to drive in, £1200 insurance is a bit steep for the MR2 with her named - for some reason she doesn't seem to think so though!

Ganzee

Last edited by Ganzeegeezer; 07-28-2012 at 02:29 AM.
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#4 Old 07-21-2012, 07:20 PM
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#5 Old 12-06-2012, 03:10 AM
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Need instructions

I would love it if you could find the time to post the full process of getting the head off without dropping the engine. I have spent every bit of free time I've had over the past 3 weeks trying to find out if this can be done, and if so how to do it. You would be a true life saver.

Thanks!!!
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#6 Old 12-06-2012, 10:11 AM
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#7 Old 04-11-2013, 05:40 PM
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It was late when I posted that, I didn't mean head so much as just getting the pistons and rings out... I still haven't started the job, because the car started a new problem the same week I was going to start the rebuild, and it has taken me forever to fix it, and I'm still not completely sure its fixed.

But when taking the engine apart this way, do you need to support the engine with a jack stand or jack when you take engine mount out? Or are the other engine mounts strong enough to support the weight of the engine without bending or warping? If you do have to support the engine from below, then do you need to put an engine mount back on when dropping the oil pan?

Also, did you need any special service tools or special tools to get the crankshaft bolt off or back on?

Sorry if these are stupid questions, I've never rebuilt an engine before... Other than this car, I've been able to fix any type of computer, appliance, machine problems I've ever come across, and have done some basic auto repair work, so I figure moving on to working on an engine sounds fun... I've read through the entire factory service manual about 3 times and read the part on rebuilding the engine about 7 times, so I think I'm ready for this... I'm just afraid of messing something up or having the engine fall on me while I'm underneath the car...

Thanks in advance for your help!
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#8 Old 04-11-2013, 07:48 PM
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You need to support the engine if you remove any engine mounts, whether using a hoist or stands.
Does the manual recommend pulling the engine from the top or bottom?
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#9 Old 06-02-2013, 02:03 PM
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manual says drop it from the bottom, which I don't have the equipment for... I'm stuck on the crank bolt right now, no room to get a breaker bar and socket on it... Any thoughts anyone?
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#10 Old 06-02-2013, 02:14 PM
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I got rid of my Spyder in '06.
If you can't get to the bolt, you may have to remove the engine mount at that end to lower the engine enough to get at the bolt. Make sure to support the engine.
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#11 Old 06-30-2013, 10:04 PM
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I finally got my buddy who's ex special forces to come by and get that crankshaft bolt loose... I was stuck on that for months...

Now I've been able to inspect/measure everything except for the main bearings, the rod bearings had deep wear, so I'm assuming the main's will be just as bad... Only problem is that judging from the service manual, I need to have the block upside down to take out and reinstall the crank to replace the mains, and the block is still in the car, and I don't believe I have the equipment to get it out... I also have the transmission still in so I don't know if I have to take that out first...

Anyone have any advice?
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#12 Old 07-01-2013, 01:30 AM
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In most cases, it's easier to remove (and install)engine and transmission in one piece.
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#13 Old 07-18-2013, 09:18 PM
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Wish there was a write up for this

'01 GS430
'07 Acura TL
'98 3.2 TL
'07 Rolla LE
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#14 Old 07-28-2013, 06:44 AM
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The pre-cats are also known to disintegrate and draw in metal substrate particles during reversion. Once the catalysts overheat multiple times (from high RPM operation), they'll start to fall apart and block up the exhaust. This also causes high oil consumption. You can check for high back pressure by doing a simple vacuum test.

The 1ZZ uses Denso 16 or NGK 5 heat range plugs, which are very hot. If your pre-cats haven't been damaged, you can move up to a colder plug that most other Toyota engines use Denso 20/NGK 6 range. That should reduce catalyst temperatures a great deal, up to 200C at high RPM. I'd only recommend this if you drive the engine harder than normal. If you keep the revs too low with the colder plugs, soot might form on the tips and you'll get misfires until the plug gets hot enough to self-clean.

Most people just have them gutted or removed completely and rely on the main cat.

1991 Toyota MR2 V6
Ported, rebuilt MY2000 3.0L 1MZ
Fully OBDII compliant and California smog legal
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