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Generation 2 Pajero NH - NL Models 1991 - 2000

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  #1  
Old 10-05-19
disco stu disco stu is offline
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Location: Wollongong
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Default Valve stem seals-how to

So I thought I would do a little "how to" on valve stem seals on the 6g74 engine after going through all the motions with mine. Meant to be a pretty common issue with these engines (magna smoke!). Might save someone a bit of time, as my time per valve went from about 25ish min or more down to about 5. I used the rope method, not having a compressor

**photos didn't work how I intended. Links are there, I'll try embedding later on**

First of all the tools. I made my own valve spring compressor. The pressure needed isn't as high as what I originally thought. I wanted plenty of room in there so used nails and welded with the worlds ugliest welder-making the worlds ugliest welds, as you can see. Washer is tacked onto the end. This worked well

https://photos.app.goo.gl/1gysUhsLCZnbdreFA

Pretty self explanatory. The part at the front is from a belt tensioner from a toyota, one hole is threaded the other the bolt just slips through. I had to play around drilling holes to get everything to line up nicely, and found that all I had to do to switch between exhaust and intake was turn the front belt tensioner thingy around. Bolt sticking through gets threaded into the holes that hold the rocker gear down, closest one to each valve

Next is what I used to pull off the old seal. Pretty proud of my bodgy solution to this problem. As the rubber hardens these are on tight, real tight. You can buy valve spring seal pliers, but they aren't cheap and honestly with the pressure needed to get them off I think what I made are better as you can lever them easier. You would have to the hulk to get them out with just straight pulling.

https://photos.app.goo.gl/1EgPEmc2eWUuX9Hb6

Get some of these long vice grips. I payed about $20 for a set of 4 from bunnings. I then ground into the end the made a little lip that goes around the bottom of the old seal, as shown here

https://photos.app.goo.gl/F3xAsd4g7RqJjWNK9

I just used a dremel and it took 5-10 min. You don't want the lip too extreme, about the thickness of the seal metal or slightly less.

Now for the rope part.

https://photos.app.goo.gl/zxWPCvanKuewTuNx5

Thats the setup I ended up with. The pipe just makes it easier getting down to the spark plug hole without the rope kinking etc. I used fairly soft cord that was about 6mm diameter

You want the piston at the bottom of the cylinder

Process that I found works best is to keep pushing in the rope until it doesn't want to take more in. Crank piston up to compress rope, then go back about the same amount and keep feeding more in. Do this about 3 times and it will fill the cylinder best. You obviously crank the piston up as high as you can when removing valve spring etc.

Note here that you want to put rags into all the oil drain holes. You will drop collets, and if you drop them down these holes you will be pulling your sump off, so make sure you plug them up.

Once rope is in you are right to compress valve spring using the compressor. Might need a few pushes to get the collets loose. Once they are use tweezers to grab them out. Magnets sucked I found, and kept sticking to everything. Once out you can release pressure and pull out valve spring

https://photos.app.goo.gl/EBs1QVsprE6bnrQk6

Use a bit of small hose to put straight over the valve stem. Don't want to scratch it up.

https://photos.app.goo.gl/dDy5FwV9MrcGCoKW7

Use pliers or whatever to grab the seal and try twisting it to loosen it up, they seem to stick on there tight

Then clamp the modified vice grips over the valve stem. You want the lip just over the seal. Don't need these up stupid tight, a little firm seemed to be enough, and you don't want to bend the seals and make life harder

Then use a lever to pry the seal off. They will need a few goes. Protect the head so you don't gauge it out. This photo is for exhaust. Intake is different and will follow

https://photos.app.goo.gl/jPXSKYGLa2gtU3jWA

For intake side I stuffed around for ages, but finally cottoned on to a strong bit of cord in a loop between jaws, bit of timber sitting in the valley, and lever through the loop onto the tiimber. Worked a treat and saved a lot of time

https://photos.app.goo.gl/4AagCN8TqEibVZCB7

To install new seal, you want something over the valve stem so you don't tear the new seal on sharp edges. Bit of heat shrink was perfect size

https://photos.app.goo.gl/Td3z8iLRWMxdRxnj8

Put seal into some oil, both top and bottom to lubricate it when being installed. Slide it over the heat shrink and down the stem. They were tighter than I expected. They are real tight onto the valve stem guide at the bottom. Bit of brass pipe was perfect size to just hit the edge of them, and I tapped on that with hammer to install. Note you're not hammering in a nail, you only need to tap, not whack hard.

https://photos.app.goo.gl/Z1n7yd9jwRgsc5kz8

Put spring and retainer back on. Now for the painful part.....put the collets back into the top as far as each will go, before compressing spring.

https://photos.app.goo.gl/yEjL4M8oN7uu4x6i9

Now you can compress spring, but put your finger in on top of the collets and press down as you are compressing. This will keep the collets in the spot where they belong the whole time you compress. At the start both this and the removing intake seals was where I was spending most time, got pretty frustrating. If all goes right and you can press both collets evenly, once you compress past the groove in the valve stem they will just pop in and you can release the compressor and job done. If not, one collet will be in place and other will need a little encouraging to get down past the groove. Just use your tweezers or whatever to push it down. Plastic tweezers are better because they won't become magnetic-if magnetic they end up causing all sorts of hell by pulling the collet back out when you pull tweezers out.

https://photos.app.goo.gl/iyJUc2yZW3ppLBFy6

Once both collets are in place, just slowly release pressure to make sure its all seated in nicely. If all is good, you've finished one valve-23 to go!

I found this a very long process until i got things figured out. I wrote this in case someone else is keen to have a go, hopefully can save them a fair bit of frustration and time

Stu

Last edited by disco stu; 10-05-19 at 10:06 PM.
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Old 11-05-19
erad erad is offline
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Brilliant writeup. Well done. When I had my NL engine overhauled, my friend (the real mechanic) used a ring spanner and gave it a smart whack with a hammer. Don't know how it happened, but the collets finished up sitting on top of the valve spring retainer washer. The head was on the bench at the time, but it was so easy. When I next talk with him, I'll check what he did and if possible, post it up on this site.
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Old 11-05-19
disco stu disco stu is offline
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Thanks Erad, appreciate that.

I also read about someone saying that they used a magnet inside a piece of pipe, and put that over the retainer and hammered it to remove. Sounds like the same deal. I'm really intrigued by that, so keen to hear what your mate says.

That thing I read also said to reinstall them, put collets in like I started with, then a piece of paper over the top, then a piece of pipe. Push down on pipe to compress spring and pull off and collets installed. I figured it might have come down to the engine they were working on as it seemed like on this engine that the collets would push up and out on compressing and tear the paper. I was intrigued though, and thought maybe a piece of balloon rubber might work. I was close to trying given how long it was taking me at the start, but when I got faster with different technique I didn't bother. Scientist in me wants to try though.

Keen to hear of others have tried either method
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Old 19-05-19
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Clarken Clarken is offline
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We were so close to doing it this way on the nk but decided not knowing the service history we may as well do the head gaskets, water pump, timing gear and as many seals as we could find at the same time before putting her on the road - lucky we did because although the only issue we were aware of was one of the rhs stem seals we found the lhs head gasket was bloody close to failing...

But an absolutely great write up anyway!
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Old 19-05-19
disco stu disco stu is offline
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Thanks, appreciate that. Damn painful way of doing it! I felt obliged to do some write up to save someone else learning it all again themselves.
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