Tune-up, gaskets & valve stem seals 6G72

[r0llinlacs]

So I finally saved up the money to do a tune-up and replace all the bad gaskets and seals. I'm still not 100% sure if my valve stem seals are bad but it definitely seems to smoke after idling for extended periods of time, so I will assume they are bad.

I'm thinking of ordering the full gasket set which includes the head gaskets, valve stem seals, valve cover gaskets, cam seals, head bolts, etc. BUT, what I need to know is do the heads have to come off to do the valve stem seals? If they don't have to come off, is it easier to do the valve stem seals with the heads off? It has 200,000 miles, so I wouldn't be opposed to doing the head gaskets as well, even though they are fine, but if the heads don't have to come off I may skip the head gaskets and order the other gaskets separately. I was kind of thinking of just doing a full top end cleaning and rebuild since almost everything has to come off to do the valve cover/rear cam seals, so I figure I may as well just pull the heads since they'll be right there, and have them cleaned and do the head gaskets while everything's apart.


If the heads don't have to come off to replace the valve stem seals, should I just leave the heads as they are, and not worry about the head gaskets? How common are head gasket failures on these engines?

Any input is appreciated. Just need to know if I should order the full gasket set or just do the valve covers/valve stems/cam seals and call it good.

[jkdv8]

There is a trick if you have an air compressor. They make an adapter that screws in the spark plug hole and attaches to the air line. Think there is a vid on YouTube about it. You do need a good size tank and it is recommended to have two people. One to do the work and one to maintain the compressor at the right psi.

[petero]

I did my valve stem seals without removing the heads back in 2013. Here's a link to my posting on the subject: msport97.proboards.com/thread/10100/notes-after-replacing-montero-sport
I used the compressor trick that jkdv8 mentioned, and it worked pretty well. The spark plug adapter came with one of the valve spring compressor tools I bought. I did the whole job alone, and I used a cheap little old Harbor Freight pancake compressor, but I would recommend you have a helper and better compressor like jkdv8 says. My post explains why. This job is not for the faint of heart, but it sure did stop 100% of the smoke. The valve stem seals that I removed were rock hard after only 120,000 miles.

--Peter
'99 MS LTD 3.5L

[r0llinlacs]

I've talked to my buddy and he makes it sound like it's not a big deal to do (but he's far more experienced than I am). All I have is probably the same compressor you have, the cheapest Harbor Freight special 3 gallon 100psi. I noticed your write-up is on the 3.5l, I have the 3.0l. Are the heads the same?

This is highest on my priority list as I don't want to get pulled over for smoking exhaust.

BUT I don't want to get off topic about the head gaskets because I still need to decide what I'm going to order before I can start working on it. Do the head gaskets go bad often? I haven't seen or read much about them going bad so if I don't get a reply soon I'll probably just skip them.

[bdmontero]

Head gaskets are RARELY a problem. It is uncommen to see a bad headgasket. Mine has 191,000 and runs like it's brand new. Get the compression checked. If it's good on all cylinders...leave it alone.

Sent from my SM-N900V using proboards

[r0llinlacs]

Awesome, mine is at 200,000 but I'll take your word for it as I haven't seen or heard much about them going bad.

[bdmontero]

I'm not saying don't do the valve stem seals. It is up to you if you want to pull the heads off or not. I highly recommend doing all other maintenance on the montero though. Especially the timing belt and spark plug boots and spark plugs. Tensioner and etc.

Sent from my SM-N900V using proboards

[r0llinlacs]

I finally ordered the gasket set. This seems like a daunting task, and I'm not afraid to say I'm a bit intimidated. Only because EVERYTHING is on top of the motor... gosh, I don't dig the layout at all.

The main reason I ordered them is because today it was smoking bad, worse than ever. I was leaving huge clouds of smoke behind me when I first took off. I added some "no smoke" stuff and drove it hard around a few blocks to burn the oil out of the combustion chambers, which IMHO is a bit ridiculous to have to do, and it worked, but I shouldn't have to do that before I drive, and it's very embarrassing, so time to fix it!

I've acquired a different air compressor since I first posted. The one I have now is a 1.2 gallon Bostitch Trim Air 150psi "high output" compressor. It's got a smaller tank than my old one, but more pressure and it fills insanely fast which is why I wanted it. It only takes about 30 seconds to fill from completely empty, so I'm hoping it will have no problems keeping up if the cylinder leaks, or if I accidentally move a valve while the cylinder is compressed. I did read some horror stories about the valves falling into the combustion chamber because someone nudged a valve that was under pressure, and another story about a guy that had a small leak and was worried his compressor was going to fail due to being on the whole time to keep up. I will try the air compressor first, but if I don't feel safe I will do the rope trick.

Did anybody have problems with the air compressor keeping up with small leaks?

Also, the tool to compress the springs... where do I find it? Some people were saying just use a socket the size of the spring, but I don't see how you could stick the retainers back on with the socket covering the top of the spring. The tool had an opening to get your fingers in there.

[jkdv8]

Taking the hood off should make it easier. You want test to so if there is a big leak you don't find out at the wrong time. I believe the auto parts places rent the spring compressor tool.

[r0llinlacs]

Alright. I'll definitely compression test it before I start pulling stuff apart. But gah, even just getting to the spark plugs is a huge pain!

And alright, thanks, I'll have to check with the parts store when it's time.

Also getting plugs and wires as well, any recommendations? I've got the NGK iridiums in mind, they've never failed me and people seem to recommend them. What about wires? Will cheap e-bay "performance" wires work well?

[pinstryper]

Search for valve spring removal tool. It has 2 arms that clamp the spring and you turn a knob that compresses the spring/ retainer is then you can remove the keepers.
Before you start compressing any, whack the retainersnwith a deadblow hammer to loosen the keepers. Easier done than said..
But do not use cam seals that are not mitsu sourced. The guys at both my stores say they are the only one's that work.
Another point is if it smokes that bad, your probably past the vavle seal stage.
I cured mine by runnjng. 50w slower a lot of leaks also.
I would run a leakdown, rings mite be toast

[r0llinlacs]

Oct 7, 2015 21:09:50 GMT -5 pinstryper said:

Search for valve spring removal tool. It has 2 arms that clamp the spring and you turn a knob that compresses the spring/ retainer is then you can remove the keepers.
Before you start compressing any, whack the retainersnwith a deadblow hammer to loosen the keepers. Easier done than said..
But do not use cam seals that are not mitsu sourced. The guys at both my stores say they are the only one's that work.
Another point is if it smokes that bad, your probably past the vavle seal stage.
I cured mine by runnjng. 50w slower a lot of leaks also.
I would run a leakdown, rings mite be toast

I don't want to think about anything worse than valve stem seals! I'm pretty sure the VSS's are the problem because the more I drive it, and the less I idle, the smoke goes away. Also it only happens after idling for so long, or if the car sits for a day. My friend came to check it out with me earlier, after I drove it, and he doesn't believe it's the VSS's because I couldn't get it to smoke while he was here. Just my luck. He thinks it's a head gasket which I know it's not because there's no coolant leaks, no coolant in the oil, no steam from the exhaust, and it has all the power the 6G72 has to offer. Hopefully the compression test will confirm this for me. Also I've been told head gaskets rarely go bad on these, but valve stem seals are notorious for going bad. It just has to be the valve stem seals.

I'm not sure but I think the gasket kit I ordered only comes with the front cam seals which aren't leaking, I know the rear ones are leaking so I may just have to get the rear cam seals from Mitsubishi anyways.

I'm just using 10w30 with a little bit of "no smoke" which has the viscosity of honey and that seems to do the trick for the most part, I'm using far less than it recommends. It did smoke really bad today when I first started it and I noticed the smoke before I even pulled out of the driveway, so I added the "no smoke" and drove hard for a few blocks and it did go away after a few minutes, so that points to the VSS's, I hope. I definitely don't want to doubt my diagnosis after ordering the parts, lol!

I'll have to remember to do the leak down test when I'm doing the compression test.

But anyways thank you all for the help and tips. Couldn't appreciate this forum more!

[bdmontero]

Do a can of restore V6 can at Walmart. Grab a 5 quart bottle of valvoline high mileage 10-40 oil. Run sea foam through your oil first. Drain it and do oil change with QUALITY NAPA filter. #1334 I believe. Add in restore and run it. I bet you will see a HUGE difference. I've done that since day one and have had zero smoking or problems from my engine.

Sent from my SM-N900V using proboards

[r0llinlacs]

So, I finally started working on it. The first thing I'll say is this engine is ridiculously hard to work on. Two hours just to remove the intake and the plethora of things bolted to it, just to have access to the valve covers. A buddy has a sister that has a 2wd 99, and he said they were quoted $700+ for a spark plug job, and now I see why.

It was plainly obvious from the beginning that this thing has never been taken apart before. 206,000+ miles, and it's still a virgin. Good, because it's never needed any serious work done to it, but bad because it's been neglected maintenance wise. Every single spark plug gasket on the valve cover was bad. Every single plug was absolutely drenched in oil, the worst I've ever seen. I'm surprised it was even running, and even more surprised it wasn't smoking worse than it was.

The good news is it's getting easier, 6 valves done so far. The air compressor is working great at compressing the cylinders, and it's not turning over the engine, so I shouldn't have to mess with the timing, I hope.

The bad news:

I lost a retainer. My friend knows a machine shop and he says they'll have them, so I shouldn't have to order an entire valve set.

The valve spring compressor tools from the parts stores suck. I've had much better luck with a $6 valve spring compressor for GM V8's, but I also bent a bolt from the rocker arm assembly using it, so I'll have to find a replacement bolt.

There ARE leaks, on every cylinder so far, but it's coming through the spark plug hole. I'm not sure if this is normal, or if it's my fittings or what the deal is, but I can hear the leak coming through the spark plug tube and the air compressor definitely has to keep up with it. It's been kicking on about every minute or so. Input on this would be appreciated.

Anyways the project is going. Here's a few pics.

Before


After the intake


After the fun began

[pinstryper]

The guys at the dealer are none to keen on doing my seals.
Find that keeper, if it gets in the engine your work is for nought