Partial Rebuild!!
Hello everyone! I've been on the forum for a short while and this is my firsth thread. I live in western Canada and own a 1998 LWB JDM IO with a 1.8L GDI engine. I have had a bit of problems with the engine thus far, let's just say that the engine is increadibly dirty from the throttle body to the intake valves. I cleaned the intake manifold, the plenum and throttle body a couple weeks ago. There was at best 2 mm of caked on soot and oil in the intake, mostly from the EGR and PCV (soot and oil). After the cleaning I put an oil detergent in the enigne oil in an attempt to remedy the the noisy lifters. That was my mistake. Instead of draining the oil I left it and drove with it for about a week. The instructions on the detergent didn't specify how long to use it for. Now all of the seals (camshafts, crankshaft) and gaskets (rocker cover, head, oil pan) are leaking or sweating at best.
After feeling like an idiot and researching stopleak additive I decided to change the seals and gaskets and preform a thourough clean of all of the intrake components, head and valvetrain. I have this week off from work as I am in between jobs, thus there is ample time to do this. I've ordered a gasket kit and timing belt kit for the job. Parts are coming from the UK they are ADL Blue Print versions of Mitsubishi parts which are of exceptional quality from past experience.
They should arrive by Thursday of Friday, then I will start the work.
I have been studying the service manual from the Tech section as well as gathering general knowledge on disassembly/reassembly, removing and installing shaft seals, liquid gaskets, cleaning valvetrain and lash adjusters, etc. The service manual is quite helpful, but theory is never like practice...
I will be removing everything on the top end up to the block, the entire sump assembly on the bottom, all of the belts and pulleys as well as dropping the transmission to get at the rear crank seal.
If you have done this type of job or have any insight into what I will encounter and how to deal with it, I would greatly appreciate that knowledge. I will try to do a clear write up on the procedure for any one who is curious.
The thing with the leaking is
The thing with the leaking is that it began shortly after I used the detergent. I drove the IO for about 2000km before this and there was no signs of leaks. I believe that the PCV system works, as there is deffinately vacuum in the crankcase, verified by removing the inlet PCV hose and vacuum at the filler cap. I have cleaned the PCV and replaced the check valve, that was one of the first things. I have heard of the dipstic being pushed out because of excessive positice crancase pressure and this has not happened. Also the IO has only 100 000km on it, so the rings shouldn't be worn, in theory...
I would like to do a full rebuild, if only to make certain that the engine is perfect, but tracking down the parts will cost more than I can afford at the moment. So this will have to be it. I should do a compression test before I start though, would be a big shame to find out that the compression is low. In the condition it is in now I've been getting 9L/100km in stop go city driving at -10C, 7.5L/100km on the highway using 94 AKI gasoline and a little less on 91 AKI. I am happy with these figures as long as there are no leaks or oil burning due to leaks. By the way, do you by chance have oil in the intake plenum, just below the throttle body? I have this constant puddle of oil there and can't figure out where it's from. I know it's not the PCV as I've tried disconnecting and venting both lines to atmosphere and running it for a few days like this, the oil comes back. Now I'm thinking it's one of the seals in or on the head. But why it's sucking the oil back into the plenum through the intake confuses me and everyone else I've spoken to.
It would be interesting to see a swap to a SOHC. What about mating a Mivec head and harness to a 4G93 block from some other Mitsubishi? Do you have many IOs in the Carribean to choose from? TR4? I know that the vast majourity of JDM IOs are GDI and Automatic transmission, which is a bit unfortunate. Although the 4G93 GDI is apparently a good engine if it runs properly.
Oil in the intake plenum is further evidence of blowby...
There are four ways to get a substance into the intake plenum ...
1) Via the air intake
2) Via the breather
3) Via the PCV valve
4) Via the EGR.
If the substance, in this case oil, is entering via path 1 or 2, there will be evidence in the aluminum plenum that sits over the engine - you say you're finding it below the throttle body, so I believe that removes 1 & 2 from consideration, leaving 3 & 4 - there shouldn't be a signficant amount of oil in the exhaust for it to enter via the EGR, and I have a recollection of your mentioning your EGR as being blocked, so that leaves the PCV.
I don't recall oil in the intake plenum on my car, but I've never really looked - I'll see if I can find the time to check it tomorrow and get back to you - if it doesn't happen tomorrow, it probably won't happen before Christmas, because I fly out on Wednesday.
Excessive blowby is the most common cause of oil entering the intake via the PCV, however it is not the only cause - the problem is I don't know how probable the other cause is with these engines. If for any reason oil does not drain from the valve covers back to the pan, it will puddle at the back of the head because the engine is mounted at an angle, and that is where the PCV valve is located.
On the Suzuki H-series V6, the PCV vents the engine via a baffled space in the valve cover and there is a known problem with the baffles sludging and allowing excessive oil to be drawn in via the PCV - the test on these vehicles is to fit a "catch can" in the PCV line between the valve and the intake and see if it fills with oil - which might be worth a try on your car.
There is another way to get oil in the intake via the PCV without blowby being the cause
Hmmmm.... I have fitted a
Hmmmm.... I have fitted a catch can to the PCV and it catches way too much oil than is normal. Something like 5ml/40km of city driving. After fitting the catch can I checked the plenum and there was the same oil puddle. So I decided to disconnect the PCV entirely. That means both the PCV valve and breather lines on the valve cover end are vented to a catch can and then to atmosphere and the orphices on the intake resonator and intake manifold were plugged. The oil was still there. I doubt very much that the EGR would be the cause because it is plugged with soot.
This is why I am confused... The resonator is dry and oil free, the only trace of oil is the plenum and beyond into the head. All of the gaskets are leaking, including the valve cover and head. Maybe there is some way and condition of running/driving that oil might be pushed into the intake manifold and plenum? Thanks for your help on this. The more ideas the better!
No oil in the plenum - at least not that I could see
I'm looking through the throttle body with the throttle plate open wide - no evidence of any oil, but an even coating of soot.
Also I really don't see any other possible sources of engine oil - even leaing valve seals would/should not cause oil to collect in the plenum, given the design of the manifold, any oil leaking down the stems should be drawn into the chamber both by gravity and air flow.
Any possibility it's a different fluid? - Brake fluid? Gear oil?
You've got me thinking about the brakes...
The only other connection, other than the purge valve solenoid, that I haven't checked is the brake booster vacuum line. I read a little into it and there is supposed to be a check valve there. Maybe the oil that I am seeing is actually brake fluid, due to a leaking valve?! That would be more probable/logical than any of the other hypotheses that have come up so far. I am not sure, but if I recall correctly the brake booster was sweating a little the last time I saw it, but I neglected it as the level was always constant. I will investigate. Thanks for the ideas and have a good trip!
If the brake fluid level is not dropping ...
Then it's not brake fluid pooling in the plenum.
There should be no brake fluid in the booster - that works with vacuum & atmospheric pressure only - so a leaking check valve will not cause fluid in the intake - take another look at the vacuum lines - there should be one that connects to the free-wheel control solenoids which are mounted low down on the inner right fender - the solenoids control a vacuum actuator on the front axle that should not have any oil in it, I don't know if it is possble for it to have oil due to a leaky seal somewhere.
The axle oil is also a pretty heavy oil - not very likey to make it all the way up through a narrow vacuum line.
Half way!
So I have basically dissassembled half of the engine in about 4 days. This is not as efficient as I had hoped. Even armed with the repair manual the progress is slow going as all of the bolt and nuts are new to me. But the progress is steady.
I had quite a problem with removing the harmonic balancer and camshaft pulleys without proper tools. After a few structurally unsound improvised tools I ended up jamming the engine via rope in the cylinder through the spark plug hole. The trick with this method is to make sure that you are jamming the cylinder at exactly top dead centre of the compression stroke. In this position both valves are closed and there is no chance to damage them. Also a friend recomended clamping one of the engine mounts with a C-clamp to prevent the engine from rotating while you apply torque to the pulley bolt. Released quite easily.
The camshaft sprockets are not so easy as they can't be jammed, thus a strong sprocket holder is nessesary. I built one with a 10mm x 60cm flatbar and 2 15mm thick bolts. Worked very well when the bar was braced against the battery platform with a piece of wood in between.
There are a lot of disassembly required to remove the head: intake tract, throttle body, intake manifold, exhaust manifold, high pressure fuel pump and high pressure regulator, power steering pump, camshaft sensor, coolant connections and the timing belt. Some of the pieces are very difficult to get at with tools. Because of the longitudinal configuration of the engine there is very little space between the firewall and rear of the engine. I read in the manual that it is possible to jack up the transmission to increase clearence in this area, but when I tried it lifted the chassis as well. Does anyone have any ideas on this??
So the head is off at this point and I am washing all of the parts. It is not as dirty under the valve cover as I had inticipated, but the PCV baffling at the top of the cover is full of oil deposits. I have been soaking it in solvent for the past thee days as the baffles are rivited to the cover and can not be removed.
I was very surprised to find that the lash adjusters or lifters in this 4g93 have 3 mm holes! And I was thinking of replacing them... I do not think they were ever changed as there are no signs of previous disassembly. I have not yet attempted to clead the lifters so I can't report on what comes out. The intake ports and valves are increadibly dirty though! There is about 4 mm of carbon buildup on and around the valves! I'll post some photos tomorrow. The seals and gaskets are very brittle and crack very easily, all are wet inside and out. Other than that the engine looks to have normal wear with nothing serious.
I am very excited to put it all back together and see, feel, and hear the improvements of cleaning. Oh and also, I would like port match the intake and exhaust as well as polishing the intake ports towards the valve. I have read that a smoother surface will help with preventing carbon buildup and this stuff seems to be this engine's bigges enemy. I am also planning to block delete the EGR as well as install an oil catch can that I will make from an old, glass style diesel fuel filter. Hopefully it will yeild the result.
Syndicate
Just a suggestion...
Leaking/sweating past every seal & gasket actually points to high levels of blowby and/or a blocked PCV system - you're embarking on a fairly extensive job - it would be a shame, if at the end of it you still have problems - if you're going to do that much work - why not make one job of it and do a complete rebuild?
I'm sort of at the same point you are - I have a 1.8 GDI, that runs reasonably well, but burns a fair bit of oil, smokes on start up, and pulling away from a standstill, which suggests valve seals, but the amount of oil required to top up, suggests rings - the power is there so I don't see the compression as being low, although I have not gotten around to doing a compression test.
The other option I have been toying with is trying to track down a front cut for a SOHC iO, preferably with a manual tranny, rebuilding that and then dropping it in.