Hi,

I'm new here so thanks in advance for any advice. I have a 98 Montero 3.5, auto all stock and it has 144K on the clock.

At about 120K (warm engine) it started to puff blue smoke, but only after I sit at a stop light for a minute or so. If I kick it down and go like h-ll it doesn't smoke. If I'm stuck in traffic it will even smoke at idle and then really puff when I accelerate, but it clears up under a load.

I bought it used with 70K and change the oil regularly. It has never had a whole lot of power, so the power seems normal and the mpg hasn't dropped off either. I have seen many other Monteros do the same thing ,as well as, the Dodge mini vans. Is it something with the 3.5 engine? Does it need a rebuild? Can it be rebuilt? Is it common and simple to fix?

Thanks,
DC

Hey there
this is a common issue for the 3.5 V6. Mine did the same as smoking after ideling at traffic lights or so.
There is no need for rebuilding your engine. the problem is oil dripping into the cylender though your valve stem seals, that causes the oil to burn and creat the blue smoke.
So the main problem is your valve seals which need to be replaced. But replacing them is a very challeging thing to do.

If your engine is a SOHC then the problem is not that hard, but if you have the DOHC motor like me then it a very very big job to do.

try using full synthetic oil , like mobil 1 or amsoil , they do not burn nearly as much as regular oil, plus it will run smoother and get better mpg

??Do you mean it won't produce as much smoke? If it drips past the valve guide seals into the combustion chamber, I assume it will burn.

But as has been noted, it's a valve guide seal issue although others have mentioned it may be a good time to consider inspecting the valves as well. I don't know if this is the case but I'll let you and your mechanic be the judge. I know for me, I'd rather replace the seals (3.0L SOHC v6) than the valves.

I would say it is valve seals. I'm about to find out, my watertemp went faulty and I cooked the engine with the temp reading normal!! It used to puff smoke when pulling away from lights. As I have got the heads off as they need skiming I will replace the seals. Getting the heads off is easy --- getting to them a different thing altogether!!!

I had the same burning oil puffs after a long idle with no obvious oil burning under a load in my 98 Montero. After changing out the PCV it has stopped. I am still going through a quart of synthetic oil per 1,000 miles but the baby is running strong (and puffless) at 160,000 miles.

My '95 3.0L had identical symptoms. Started noticing some smoke around 170-175k. By about 180k the smoke got pretty severe. PCV made no improvement. At around 190k I finally made time for the repair.

I was able to replace 23 of 24 valve seals with the heads in place (and a $70 spring compressor), and no prior internal engine work experience. The 24th was DS against the firewall and just couldn't get the spring compressor to it. Took most of a weekend, but oil consumption dropped by 1/2 and all smoking problems were gone.

Edit: Wow, this is old.

I have a 97/ SR with 113k, I noticed smoke after idle. Added 1 quart of Lucas oil treatment for two consecutive oil changes. Problem solved and engine runs smooth as silk. May be a quick fix, but easier and cheaper than getting to valve seals! Try Lucas...it's worth it. Just sub 1 quart Lucas for one quart oil on your next change.

I owned a '92 Mitsubishi Montero, which I bought at 58K, the seller cleverly sold before the recommended timing belt change at 60K was due. Anyway, I loved the SUV's 4WD and solid feel. I tend to drive brutally, so I blew the engine at 112K, then blew the rebuilt about 35K later. I then
bought a '96 SR 3.5L w/ 113K, and I love it even more, although there are weird little problems that
I figured would be solved in 4 years time. One problem is the leaky valve guide seals that smoke and burn oil. It's worthy of a class action suit, but who has the time. In my stubborn refusal to be
suckered again by bad valve guide seals, I first used Techron fuel injector cleaner several times, and recently found the most amazing motor oil online called Silver Series, invented by Ron Spence.
It uses silver instead of zinc in the formulation, so my exhaust stopped smelling, the engine quieted down, and stopped burning oil! Not expensive either. After the first 300 miles I noticed a pleasing smoothness that got even better after a thousand miles. I used the 5/30W and am thrilled. I've
used all of the store-bought stuff for thirty plus years, and now I think this Silver Series would help
any engine tremendously. Run cheap oil through first if you've used Mobil 1, as per instructions of Ron Spence.
It's not a guaranteed fix, but this formulation has worked wonders for my problems.

Where did you buy the Silver Series oil?

The website is http://silveroil.info/

You can buy 2 gallons minimum initially for about $44.00 plus shipping.
It's great stuff. Good luck.

I have the same issue. My Mechanic told me to start using a thicker oil and there's a treatment that will prevent the leak. Not sure if that's the answer I was looking for, since he just charged me 700 to change my timing belt. What a mother focker...
so how hard is it to get that done? I'm not too mechanically inclined but I have some friends that can help if needed.