Turbo Replacement

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[url=https://imoc.co.uk/app.php/kb/viewarticle?a=7&sid=01e07f2e8f86a82a0b8f3d5ee929b7ee]Knowledge Base - Turbo Replacement[/url]

Replacing the turbo
by Dave Bewley

Following problems with high oil consumption I in the end carried out a replacement of the turbo. I am pleased to say this fully solved the problems.

First let me give you the symptoms, I did struggle to find advice, and this being both a major task, and not cheap I wanted to make sure before starting. Also had to convince the purse string holder too.

Problems were first noticed when occasionally when on over run I would get a slight pop from the exhaust, not a problem at that time. Oil was being used, but not much above normal levels. Also when on slow running I could see a puff of oil smoke out of the exhaust occasionally. Towards the end when at traffic lights clouds would come out, only to clear when revved.

The pressure lines to the intercooler had oil trace in them, as did the compressor side of the turbo. Most of the advice I had said that the engine was generating too much pressure and that the oil was coming through the breather. Compression was good, and I also bought a cylinder leak tester, this showed all cylinders holding pressure and therefore there wasn’t any blow by. My conclusion was it had to be the turbo. Inspection of the pressure lines didn’t show any signs thankfully of metal, it really would have been curtains then, at the compressor impellor would have been hitting the housing.

Ok so the next problem is how to change the turbo unit without removing the engine. This task was embarked without any manuals, or advice on how to tackle the job. Also the job was done on my own, and at some stages the whole job seemed impossible. In order to give some help to other owners, MR2 Turbo’s are getting older. I decided to write this document.

Removal Procedure

1. First remove the engine cover fully, and the 2 small side panels. This will help with clearances.
2. Remove all the air intake pipe work, flow sensors, and the pressure side to the intake bell. I also removed the air box to give me room to work. (Note some of the jobs I found easier to stand in the engine bay where the air box sits.

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View with air box removed.
3. Now jack up the car and place on axle stands, or better still if you have a ramp or pit its time to work underneath. I don’t and it’s a pig on your back. You need to remove the back section of the undertray. You might be lucky and the bolts come undone. Most of mine did. But be prepared to shear some off. Plenty of WD40 helps. In fact take shares out in WD40 cos you’ll use a lot.
4. Now’s as good a time as any to drain off the oil. (Tip when I do this I place some masking tape over the ignition key stating no oil. And also on the steering wheel. Seems silly, but this is a long job.)
5. Now you need to remove the exhaust, mine has a standard system, in fact the original, not bad for a 1991 rev 1 model. Its all obvious, but most of the bolts will need cutting as you come away from the cat flange. I used an air driver to remove the main flange bolts, the shock from the impact worked well. Shame this cant be said from many of the others to be encountered later.
6. Don’t do what I did and remove the outer covers on the exhaust pipe, you don’t need to, and it only wastes time on both the removal and the rebuild. Watch out for the rear box, its heavy especially when your laid on your back.
7. The main pipe is held on the cross member by a rubber mounting. You can try to slide the pipe off, but I found it much easier to remove the rubber mounting from the cross member. This is held on by 2 12mm AF bolts. They are difficult to see.
8. From the top of the engine bay disconnect the wire to the bottom temp sensor. Mark both ends of the connection to help you on the rebuild. Whilst your at it you may as well do the same to the O2 sensor wires, and the leads to the intercooler fan.
9. Back underneath, (you’ll do a lot of this) unscrew the temp sensor from the cat. It looks as if it wont move, but more wd40 and a pair of grips and its easy. I took it off because it does get in your way. If you can work around it fine. Its upto you. I’d lost plenty of skin already.
10. Now you may be lucky and be able to remove the cat now. You will need a long extension for a 12mm AF socket. If you look up at the flange you will see 3 bolts and 2 nuts all the same size, Few. I wasn’t lucky all mine were badly corroded. Don’t worry I’ll describe how to remove in one piece. (that’s how I did it).
11. On either side of the cat there are cast brackets going back onto the engine block. First you need to remove the 2 14mmAF bolts, one either side of the cat. These are tight. Next you need to remove the cast bracket from the block on the air con pump side. Again these are tight, and they are in difficult positions. In fact I found it easier to remove them from the top of the car once I removed the heat shields.
12. From above now, First take of the intercooler fan. (Again for access) Now remove the main heat shield. This is held on by 3 12mm AF bolts. 2 are easy to see. 1 is a pig. It is as the back of the shield almost on the bulk head pointing slightly down, I found the only way was with grips.
13. Now remove the end elbow heat shield this is next to the Oil Filter. The heat shield is held in place by 3 12mm AF bolts. Two are easy to find 1 is slightly hidden lower down.
14. Remove the Oil filter, and also to aid the removal of the end elbow take out the 30mm Af banjo union. This will loosen the filter housing allowing sufficient clearance for the exhaust end elbow. The elbow is held in by 6 14mmAF bolts. Some of these are difficult to get at with a socket. You will need a good 14mm cranked ring spanner.
15. Now you can remove the end elbow. If you didn’t remove the cat then you will have to lower it down. Don’t let it drop as its heavy. This work I found best if I was in the engine bay, and therefore not putting pressure on my back.
16. Now back under the car, looking up there is a cast bracket mounting the turbo to the engine block. Remove this. You can now see the 27mm Af banjo union holding the turbo oil feed to the block, undo and remove the banjo union this is very tight. Note there are 2 thin washers either side of the banjo. Also remove the rubber hose on the return side plus a 14mm af bolt holding the pipe to the block.

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17. Now you are coming to the last stages. Phew. Looking at the compressor end of the turbo there are a number of small pipes. 2 of these are the water cooling. Remove them. I blocked of the pipes to prevent water loss, thus saving draining the system. There are also a couple of vac pipes that you need to remove. Mark them with masking tape to help you on re-build.
18. Ok now is the time to remove the turbo from the block.

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19. I found the easiest way was to take the turbo and manifold off in one unit and split the turbo on the bench. Most of the nuts are easy to see. There are 2 underneath the manifold almost central 50mm apart. You may have to slightly bend a heat shield to get a socket onto them. Whilst all are tight all came away quite easy. Now you can lift out the turbo and manifold. stand back and view the back of your engine. You deserve it. You are looking at something that not many mortals have seen before.

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20. Ok back to work. Splitting the turbo from the manifold is straight forward only 4 14mm AF nuts holding it in place. 2 are simple with a socket 2 you need a good ring spanner. One of them I had to chisel off. Don’t worry Fensport can supply all new nuts and studs.

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Note this is the new Turbo Supplied by Fensport.

Refitting is the reverse of what you have just gone through. Although it seems to be much easier. It is worth taking a few precautions before starting your pride back up following the rebuild.

First refill with oil, and fit all the filters etc. Then remove all the plugs, and the ht lead to the dizzy cap. Now crank the engine on the starter motor first until the pressure light goes out. Allow the engine to stand for a few minutes and recheck the oil level. Then crank it up again this time allowing it to turn over for a minute or so after the pressure light has gone out. This will ensure you have oil into the turbo, the turbine should spin on air pressure alone, but the wont be any damaging heat. You can now refit the spark plugs and ht lead. And fire up the engine. Mine fired first time, wow. Allow it to tick over for about 10 mins to get up to temperature. Then stop it and allow the oil to settle once more. Check the levels again. Once you are happy then you can go for your spin. Again make sure everything is up to full temperature before you fully enjoy your new turbo.

All parts used in the rebuild were supplied by Fensport.

Dave Bewley
Email to [email protected]
1991 MR2 Turbo