valve guide replacement
 

I was wondering what is involved in replacing the valve guides.

I am working on an engine, it's not a mercedes engine, but soon I will be doing the same on my mercedes engine, and was wondering how this process is carried out exactly.

This engine I have in pieces now is the Mitsubishi 3.0L V6 commonly found in many Chrysler cars.

I have both cylinder heads off, and it looks like some of the valve guides have "dropped", so I want to fix this up and put the car back together.

Assuming that the valves are still good, and will not be replaced, is it just taking the valve out with the assistance of a valve spring compressor, tossing out the old one and putting on a new vlave guide and seal and putting the valve back on?

Is griding necessary or anything else like that? I will be doing this for the first time, so any hints and tips will be greatly appreciated.

xp

VAvle guides are pressed in. Some have a shoulder, some have an E-washer or snap ring, and some have to be seated to correct depth with a guage. Some just get pushed in til they stop. Engine dependent, so you must check. You will need the press tool as well -- usually a pilot that fits through the guide.

The are removed with a tool by pushing them out from the bottom.

You will probably need to grind the seat to restore the sealing surface. May or may not have to ream the guide for correct size -- MB guides will be exact and won't require reaming, but other manufactures sometimes do. Seat conditioning must be done after the new guides are in place, as they are the reference for the seat (ie the valve must sit correctly to seal).

Lapping the valves in is also required to get a good initial seal.

I'd have a shop do all this. You can install the valves yourself, but have the machine work done, it requires far to many tools to do yourself.

Valves can be ground if not too badly worn, there is a spec for how thin the edge can be. The shop will tell you if you need new ones. Intakes usually can be reused (less wear), exhuasts usually must be replaced.

Peter

pricey
 

I took both the heads to a machine shop close by, after calling a few others. They told me they would do everything on them for $4500 each. This is a $500 car and no way can I spend, not that I even have this kind of money. Additionally, it's an extra car that I would love to get working right, but if I don't then it is no big loss, just a ton of spare parts for the one my dad drives, it's the same thing esentially.

This is why I'd like to do all this work on my own, I have time since I don't need the car, my dad has all sorts of measuring equipement since he works in a machine shop like that as well, just does not deal with cars. In other words tools and other devices I can get. So it would be a much better deal for me to just resurface the heads at a specialty shop and do the rest myself.

I'll be getting the heads back on Monday, the valve parts are not pricey at all, and if I can get this car working then kudos for me :)

Unfortunately, the Haynes manual for this car does not have a procedure for doing this which would be helpful, so I will be looking for some type of a guide to replacing valve guides :)

xp

Do you do your own brain surgery also. I've heard it is expensive too.

I have had a saying that has applied my whole life to almost every endeavor. "The best thing you can know about an operation is what you don't know". What you don't know, you can figure out. If you don't know that you don't know, you are screwed. It is part of life to figure this out. You have a lot to learn.

Machinist tools won't cut valves or seats. The common measuring tools might tell you if you needed to or not, if a knowledgeable machinist were making the adaptations. I doubt that a standard machine shop would have 9mm go-no-go gauges for measuring guide wear. You might possibly have a 9mm interference reamer.

By asking the question originally you point to your lack of knowledge. Continue finding what you don't know and you will be less confident and more sure.

BTW: $4500 to repair one head, what were they doing recreating it atom by vacuum deposited atom? I don't even think 928 S4 heads cost $4500 new.

Many of the heads used in modern 4 valve applications were never meant to be repaired after major failure. I know almost nothing about Mitsu heads except that they grenade when the belts break. Working on a MB head is infinitely more doable than a Mitsu head, part of the reason the car costs 3 times as much.

$4,500. each?????????????
You must have misunderstood or these guys are either bandits or crazy or both.
You can get a complete re-manufactured engine including heads for $2,000. here:

http://www.auto-car-engines.com/mitsubishi-montero-1993-parts.html

JackD

I'm perfectly aware that I can get two heads for this car for $100 each from a junk yard, which are guaranteed. And yea, these guys are bandits, I called them and told them not to touch those heads anymore, just do the surface and leave it, they had the same price for the surface like all the other shops fortunately.

I also found a good engine for $600, but I have two cars like this, exactly alike, and the other one will probably need the same work done on it soon. I thought I'd turn this into a lil hobby project, but I'm not getting much positive feedback. I also don't want to abandon this completely, I'm looking forward to putting the car back together.

In either case, once I get the heads back on monday, I'll know which guides need to be replaced for sure. Depending on the difficulty of it I'll decide if I will do it, or put them on the shelf for a time when I have money to rebuild them for the other car while this one gets the two from the junk yard.

I also don't know if it's just me, or if in the States car mechanics are a lot more honest then here in Canada. I have yet to find ONE, that does not try to rip me off from the moment I walk in to his shop.

xp

Finding a decent mechanic is difficult, compounded by the werid phenomenon I see around here where people will both trash talk someone who does good work for them at a good price, and worship the ground of someone who charges 2.5 times LIST price for parts and $100 and hour for labor, while never getting the stinking car fixed right.

Go figure, beats me!

Peter

If your a talented person,

You can replace the valve guides yourself. I've done it and if you are careful- a light lapping and the valves will seat fine.

I would guess your valves and seats probably need grinding though..... On some engines- valves can be found for $2-5 and it's easier than grinding.

While I have not checked lately- Blaines engine supply in dallas use to be dirt cheap on parts... might want to check them out. They were about 20% of the my next closest price when I've done american iron rebuilds.



Michael

Hi samiam4

I was under the impression that valves have to be ground one way or another unless the originals are still in good shape. This should not be a problem. But if it's easier to put in new valves, I don't see a problem with that either.

In any case, thanx so much for the positive feedback.

xp

Got heads back from the shop
 

I picked up both the cylinder heads from the shop degreased and resurfaced. It looks like 4 out of 6 of the exhaust valve guides have dropped considerably. One is chipped from the valve since it dropped so low, no visible damage to the valve itself, the valves don't look worn either, but they are getting checked for specs as we speak.

My dad put together a puller for the valve guides, they are coming out without a problem, I do have a question however.
I will replace the one that is chipped for sure, but as for the other ones that dropped, would there be any risks involved, other then them dropping back down after another 200,000km if I just push them back up, put on new seals and put the head back together?

From the design it appears as if the seal is supposed to hold the guide in place from dropping in addition to it being pressed into the head.

Any suggestions?

Oh, I also heard from a mechanic that you can test the valves for propper seal if you pour gas from the top and watch if it will hold for at least 2 minutes. If the valves hold it, then they seal correctly, anyone ever heard of this method? Is this what is referred to as a leak down test? It just occured to me.

TIA

xp

I guess you could consider it a " partial " leak-down test.
A " real " leak-down test checks the piston ring sealing, as well as the valves, as you are introducing compressed air into the cylinders.
The suggested method of checking the valves/seats with gas, is a new one on me but, considering that you're checking metal-on-metal sealing, it could be correct. ;)

Use water instead of gasoline, it won't catch fire. You could use rubbing alcohol if you want something less viscous that water.

Not a bad idea to check -- there are shops that don't lap the valves in on the assumption that they will "wear in" anyway, and if they are not sealing well enough, the engine is almost impossible to start initially.

Peter

We have used a similar method. We set our head in a parts cleaner and pore some mineral spirits in the chamber (head upside down. WQe then aply air pressure at the head ports and look for bubbles. The bubbles are just easier to judge.

The valve seals provide no assistance to holding the guides in the motor. The spring rotator will peel the seal right off as the guide passes through it into the chamber.

One bit of advice I can give you is that if the guide has moved in the head you can not just put a standard guide back in. For one thing the whole WILL NOT be round anymore if the guide moved. An old tech told me part of my system and we have developed the rest. The original guides are 14.01 and 15.01 OD. The new standard will comes as 14.03 and 15.03. This is a little less than one thousandths of an inch larger. To be sure you get it secure, we get the first over guides at 14.2 and 15.2 mm. We then cut them down on a lathe til they are about .003in greater OD than what came out. With a proper driver we then beat the DS out of them driving them in. They should go in harder than the ones that were not falling out and received the slightly larger guides.

Once in, we put a reamer through to size the inner diameter and its ready for another couple hundred thou.

If your going to machine down some OS valve guides,

I'd make sure your hole is true and no metal was removed. If not, then you want to ream the hole, then machine to fit.

Steve- heat the heat slightly(250F) and cool the guide in a "chill box", the new guides won't be any problem.

Michael

back to the shop
 

I will still probably get these heads back to a shop to get the new valve guides. They will have to be reamed one way or the next.

I'll be calling the dealership tomorrow to find out if this probelm was ever fixed. If not, my dad will come up with something for sure. If not, I'll talk to the mech at the shop to see what his suggestion is. This guy has a good reputation and all the work he does is on tape in case you want to make sure you did not get ripped off.

Thanx for all the advice guys.

Although this car is a domestic piece of crap, you do learn a lot about some things that are in common with many other cars :)

xp

Michael, if you use standard guides you sure won't need any heat.

If you try and ream the head chances are your going to ruin it. The method I use as I expressed works and saves those heads. By using the extra interferance fit the guide will conform to the slight irregularity of the hole. This will cause the inside of the guide to be slightly disturbed also. That is the reason for the reaming after installation. You can heat it if you need but using the proper MB drivers there really is no need. At the proper interferance it will go in about two to three times harder than the slightly oversize standard guides do in a virgin hole (one that hasn't dropped a guide - any movement is dropping in my mind). after near 30 years of doing this and hundreds and hundreds of heads, I only offer advise. If you don't do something on those droppers, it will be one short valve job. They will be slightly out of round and I'd love to see you match the head hole to one of the oversize 14.2 or 15.2 guides. Remember that after screwing the 14.2 there is only 14.4 remaining and then its a new head or some real heroics.

Steve,

Don't bother telling someone with a few hundred hours in the machine shop how "I'll ruin the head by reaming it". It's the correct way- if you know what you are doing.

As far as having "MB correct tool." Honestly, current mechanics crack me up! You really could learn to save a bunch of $$ by learning basic metal working and heat treating. I made my 0M617 go-nogo gauge in less than 20 minutes out of drill rod, heat-treated, tempered, polished to the final dimension. Very simple and not hard. If I need a correct driver, I will just choose some steel and make one.
I had general machine shop stuff at the university and made rack & pinion, a couple of really sweet flywheels, a full set of heli-coil install tools, etc etc..
Horology school added the precision into my work- ever work with a shaft pivot shaft diameter of 0.03-0.04 mm?

I know what your saying on loose guides and for that matter-seats. Dealt with it all before.


Michael

Yea smarty pants, tell be how many loose valve guides have you fixed.

My information was delivered for those who could use it. I just talked to a guy who wanted to buy seals for a 70 dollar master cylinder because he couldn't afford it. There isn't but a few automotive machine shops that do the kind of head work you are talking correctly; let alone a bunch of DIYers. I gave the advice so standard guides wouldn't be used in a place that couldn't work.

Valve job done
 

For anyone who might be interested, I just finished putting back together the two cylinder heads that needed some repairs. In the end I decided that since this car is not worth much, not much money will be spent on it, so the old valve guides were reused. All were within specs. I made a tool to readjust them all to their correct height, and although they will drop again, by that time I hope I won't be needing this car anymore, it's just a winter beater and a back up car so I can do so quality work on my benzo. The heads were resurfaced, degreased, adjusted, valve seals were replaced, leak down test shows that they still hold very well. Tomorrow I will start putting the car back together, hopefully it will run when I'm finished with it ;)

wish me luck.

xp

Good luck. ;)
Btw. Have you found a new women yet ?

Manny you devil :)
 

Is it that obvious that I'm looking for one? :)

xp

You're always screwing around with your cars........may as well do the same with a women. :D

so true :)
 

Manny you just made my day, I can't remember when i laughed so hard :D

but it is true, now that summer is around the corner I should switch from cars to women, for some reason doing both did not work out very well for me last year :cool:

xp

Almost set
 

The car is back together, only have to reattach the hood and some splash shields which I don't care much for at this moment.

Right now the old choclate milk oil is drainning, I will leave it like that for the night and tomorrow a fresh filter, fresh oil, and I'll see if the car runs, I sure hope it does.

It took me 4-5 weeks to get all this done, little at a time whenever I could.

xp

it wont start
 

I got the car back together, put in all the fluids and tried to start it after checking the timing numerous times. It won't start.

The starter motor turns, everything spins, but it won't ignite. It floods with fuel. I know there is good compression since I checked everything and after a few seconds of cranking the starter motor has trouble turning the engine since the fuel is getting compressed but not ignited. I check for a spark and there is one, although a bit faint. I checked the timing on the distributor, and although I have never used a timing light before, from what I know it seems right.

I marked the crankshaft pulley on TDC, and although I had some trouble checking the marks while the engine was cranking, they did line up as far as I can tell. Still it would not fire.

I think one of the ignition coils might not be connected right, or the wires got broken along the way since I preatty much had to move all of them out of the way, so this is what I will be checking next. Other then that I'm not sure why it won't start.

Any suggestions what else I could check?

xp

Firing order and crank position senor -- if you have the coils wired wrong (I'm assuming distributorless igntion) the wrong cylinders are getting spark, it won't run.

If you have a distributor, make sure you have the wires in the right order and the rotor is actually pointed to the correct one (easy to get the dizzy in one tooth off, for intstance).

Otherwise, no spark is a bad crank position sensor or loose wire somewhere.

Peter

at TDC
 

So at TDC, should the dizzy be pointing right at the #1 cyinder contact?

I did have it one tooth off, I corrected that but still nothing. I'm suspecting something electrical since all the wires were moved around.

xp

Yup. Make sure you didn't get some spark plug wires swapped around, too!

Check all the wires to sensors, etc -- easy enough to pull a connector loose and not see it. You should get a nice, hot spark off any farily recent ignition system.

Also check the coil to distributor wire and plug wires -- when they get old, the insulation can crack when you move them around, and the spark will then "leak" out along the way to the plug!

Peter

No dice
 

Alright, I checked all the wires, I get a nice spark on all cylinders, yet no start.

I tried fooling around with the distributor some more thinking that maybe it's on in the wrong position since there does not seem to be any fuel burning going on at all. No exhaust fumes from the tailpipe. Although after sitting in the garage for a while it did back fire on me. intake mainfold filled up with smoke of some sort, but that was it, nothing afterwards.

I guess next I will check for fuel if any. since I can smell it, I guess it's there, but that could be from priming only. The computer does not report any codes other then batter recently disconnected.

I'm at a loss here, I need some ideas to get this thing to run.

Someone help :)

xp

The Mitsubishi/Chrysler 3.0L V6 is famous for valve train problems. Here's a link to the factory rebuild manual:

www.twingles.com/manualcd/dsmgift/6g72.pdf

Here's a DIY guide for the job:

http://www.allpar.com/mopar/3fix.html

and another:

http://www.allpar.com/eek/ValveSeals.html

Lastly, if you'd like to buy replacement rebuilt heads from a competent rebuilder at a reasonable price, here's a link to a rebuilder that many offroaders who own Dodge Raiders and Mitsu Monteros have found to be their choice:

http://www.cylinder-heads.com/automotive-cylinder-head-rebuilding.html

Good luck!
Frank

Didn't see you already had it back together so apologies for the unnecessary information.

If the one you're working on is like some of the other 3.0Ls, look at the underside of the distributor cap to find the wiring connections to the plugs. On some models they don't go in firing order around the clock, but have bypass tunnel connections under each other and are somewhat random in order.

Hope this will help and good luck!
Frank

Hi Frank

Thanks so much for the info. I do have the engine back together, and the distributor cap does have numbers on it, I just can't get it to start.

I will look over the documents you provided links for, perhaps I can find something in it.

Thanks so much again.

xp

It's alive!
 

Alright, I got the sucker to run.

Turns out the distributor marks were wrong. I probably marked it wrong when I was taking it apart.

Other then a lot of smoke, and one of the valves clapping really loud, which I will try to correct. The engine runs very well. I still ahve to adjust timing on it, and I'm guessing the smoke is from all the new gaskets because I do not see any leaks at all, and it comes from the exhaust mainfolds on both heads.

Aditionally, no more water pouring out of the exhaust pipe, not in the amounts it did before at least, no more nasty smell, heating works, although I don't need it anymore. And I accompished my first valve job, not bad :)

xp

Good job! Now solve my ABS problem, please and thank you!!

Frank

Fixed
 

Took care of the valve knock, turns out it was only oil and since I was flushing the engine, it fixed itself.

I took it for a drive and it does drive :)

But it looks liike it has a bad O2 or a dead CAT, or both, lots of exhust smoke coming out of the tail pipe, not like any of my other cars, I'm hoping it's just the O2 which should be dead from the burnt coolant.

The investigation continues.

As for ABS, unfortunately I don't know a thing about it, none of my cars have ABS in them. But I would start with electronics, the sensors, and then the computer, might be a lose solder joint.

xp

XP:

some smoke is normal from machining oil burning off, but if you have copious blue smoke you have oil getting into the combustion chambers. While smoke (or blue smoke slowly trailing down to nothing) can be crud in the cat -- it will burn off when you get it up to temp, but it may have failed. If so, the O2 sensor is also fried.

If the smoke is black, look for a bad coolant temp sensor or a broken wire/unplugged sensor.

You can check the O2 sensor with a volt/ohm meter -- it should produce 0 volts very lean and about 1 V full rich -- if you have black smoke rolling out the back and 0 V on the O2 sensor, it's toast.

If you didn't have black smoke before, check for a dead temp senor or a disconnected or broken wire on the temp sensors first.

Peter

smoke gone
 

Alright, the smoke is gone, but the exhaust funes still smell terrible, I have no idea why, but I'm sure it is not supposed to be that way.

I don't know if I can describe the smell, but if anyone knows what could be causing it, I'll be happy to check it out so this car can be used propperly.

TIA

xp

If that engine was burning oil for a long time, chances are the cat is trashed. Are you smelling sulphur dioxide.... rotten eggs?

BTW, I think your engine may have VLAs (valve lash adjusters). If so and if it's tapping, there's a trick to calm them down:

From idle, slowly and steadily rev the engine to 3,000 rpm over a period of 15 seconds. Then let it idle for 15 seconds. Repeat the cycle up to 20 times. Usually they'll calm down after only a few cycles.

Frank

cat
 

I think you're right Frank about the rotten eggs, but I would say that the cat is fried for sure since this engine was burning just about everything prior to the work I did on it.

The valve tick I fixed, it was simply oil related. I flushed the engine, put on a new filter and the tick was gone, it works real nice right now. Starts on the first turn, idles real smooth, I just have to take it for a road test to see if the transmission works at all in higher gears... I think there might be a problem with it, but that will be my next project.

I think I will stop by a local junk yard and get a used cat for this car, or engine I guess you could say, from a later model.

I hear that not everyone wants to sell these, so where would I look for a cheap cat?

xp

You can try to get a "direct fit" unit from a junk yard, but get a guarantee that it will pass emissions or your money back.

Otherwise, the most bang for the buck is a "universal fit" unit from any of the discount parts houses or even from a muffler shop. Match the inlet/outlet pipe size and make certain the hanger arrangement will work. Some of them are welded in and some have slip fittings with clamps.... just know if you're going to do the work yourself that you might have to do some fabricating (check the fittings to see what will work). You can buy them from $40-200, depending on quality.

Type "universal catalytic converter" in your web browser and you'll be entertained for a while and get some ideas.

Frank

xp190
Slight diversion to the current topic, has anyone mentioned about the retightening of the cylinder head bolts after a few hundred miles? I really do not think this is necessary but I am just gathering opinions.
thanks

As I understand the 3.0L V6 Mitsu engine requirements, a Fel-Pro gasket does not require a re-torque, but otherwise it should be done. It's a real PITA, tho'. Below is what the manual states as procedure for reassembly of cylinder heads on a 1989 Dodge Raider V6 (3.0L Mitsu):

Frank

Depends on factory design -- stretch bolts usually don't need to be retorqued, but some manufactures require it.

Best to check a manual for that information.

Peter

My manual did not mention anything about retightening, neither did the lil piece of paper that came with the head gaskets, just to make sure you use proper sequence and incrased torque specs.

I think I did an okay job overall, no leaks at all, but now my dad broke his acclaim, had to spend some time fixing it, but it's back on the road.

xp

To all,
True...manual does not mention retightening either.
FrankR, I did not work with a manual on my old Honda Civic so maybe head bolts needed to be retightened if so mentioned in the specs.