Mitsubishi Montero & Montero Sport This sport utility vehicle offers more size than the other Mitsubishi SUVs, but manages to keep a sporty look and comfortable feel, unlike many larger SUVs.

Valve seal replacement

  #1  
Old 09-19-2018, 08:16 PM
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Default Valve seal replacement

Today I had a chance to drive behind my beloved Montero (>235k miles on it) and noticed a fairly significant bluish smoke after every time Monty idled for some time at the red lights. I'm pretty sure my valve seals are giving up the ghost. I'm going to run a compression test to be 100% sure I'm not getting a significant blow by past the piston rings.

The question I have is this - has anyone here replaced the valve seals with the heads on the engine? I'd like to do this work with minimal amount of engine disassembly, i.e. with the engine on the vehicle and heads on the engine. I know its possible to do this with pumping air into cylinders to hold the valves closed or with the rope "trick". Any input/advice is appreciated.
 
  #2  
Old 09-20-2018, 05:43 AM
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Hunter - If i recall there are several Youtube videos of doing the rope and air trick on our montero's.
 
  #3  
Old 09-20-2018, 11:06 PM
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Yep, I've seen some vids of that. Still trying to figure out what is better/easier. Seems like air is quicker, but you do run a risk of dropping a valve into the cylinder. Rope trick is a little slower to set up, but seem to be more secure. Will be doing some more research on both methods.
 
  #4  
Old 09-22-2018, 06:36 AM
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I would be inclined to do the air setup myself. I'm not confident I could fully stuff the cylinder with rope to prevent valve drop.

Some food for thought:

These engines are interference types. When a timing belt fails, the piston takes out the valves. This tells me that you can't drop the valve beyond retrieval as the valve keepers of a properly installed valve will hit the piston if at TDC.

Googling, the intake valve is 33mm (1.23") and the exhaust valve is 29 mm (1.14"). The areas are thus Ai = 1.19 in^2 and Ae = 1.02 in^2.

So for easy math, let's assume each valve face is 1 square inch, so for every psi of air pressure applied, this nets one pound of force applied to hold the valve against the seat. Apply 100 psi air pressure, there is 100 pounds applied to the valve to hold it in, etc.

Do one valve at a time and obviously the cylinder needs to be at TDC firing. There are not timing marks for each cylinder firing so this will be a little difficult to determine. When I tried to find the source of my cylinder 6 mis-fire, I put a 1/4" wooden dowel down the spark plug hole and rotated the engine by hand via socket on the crank bolt with a breaker bar and watched the dowel rise and fall observing the location of maximum rise and checking the rockers for tight/loose condition at the peak rise (loose should occur at TDC firing). I then applied air and rotated the engine for/aft trying to dial in maximum sealing and never could; I could hear air leakage but could not tell if it was into the exhaust or the intake. Your engine has no compression issues so this should be easy for you. Once TDC firing is determined for cylinder 1, you can then study the firing order to efficiently work your way thru the cylinders in order.

As a precaution I would keep the regulated air pressure applied during the procedure. I would be inclined to use 150 psi to give added margin for pressure decay if you are not quite at TDC, your compressor/airlines leak, etc.

The guides are a bronze material from memory and I don't know if the valves are magnetic for retrieval should the valve tip pass into the guide. Again, I can't see this happening since a properly installed valve will interfere with the piston if the timing belt fails.

Thanks for the brain exercise.
 
  #5  
Old 09-22-2018, 03:26 PM
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Larry, thanks for the input. With you having done a major rebuild on the engine, your outlook and thoughts are always appreciated. Here is an interesting thing - I just read the FSM for the engine, and they do not require air or anything else to support the valves when cylinder is in TDC position. It seems that the cylinder itself will be holding the valves from moving anywhere. When you did work on your engine - did you use any special tools to install the valve seals, or just good judgement and your hands?
 
  #6  
Old 09-23-2018, 05:36 AM
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Hunter - see Post 73 of my thread.
https://mitsubishiforum.com/forum/mi...e8/#post314934
The Fel-Pro seals I used had a plastic sleeve that you install over the valve stem. This lets you slide the valve seal on without it being damaged by the groove for the keepers. I used a Craftsman 13 mm deep well socket to press the seal into position and you can feel it "snap" into place. I also lightly tapped the socket tool with a rubber mallet. I searched thru my sockets and that one had the best fit to the seal.

There is a factory tool for this MD998774 shown in Section 11B of the FSM but the socket and "snap" feel worked for me. The FSM is not clear but the image in the manual appears to show a hammer striking the tool to install the seal.
https://mitsubishi.service-solutions...SEAL-INSTALLER

See Post 26 of my thread for discussion on valve spring compressors. Some useful links there.
https://mitsubishiforum.com/forum/mi...e3/#post314143
 
Attached Thumbnails Valve seal replacement-fsm-11b-valve-stem-seal-tool-md998774.jpg  
  #7  
Old 09-24-2018, 05:41 AM
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Hunter - in your case you would have the rocker shafts and arms removed to access the valves. Thus all of your valves will be firmly seated for all cylinders simultaneously. Thus all you need to do is be at TDC to prevent valve drop - does not need to be TDC firing.
 
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Old 09-25-2018, 02:51 PM
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Originally Posted by larry4406 View Post
Hunter - in your case you would have the rocker shafts and arms removed to access the valves. Thus all of your valves will be firmly seated for all cylinders simultaneously. Thus all you need to do is be at TDC to prevent valve drop - does not need to be TDC firing.
That is correct. It's one of the steps in the process and I was thinking that any time at TDC will be fine. I guess now I need to decide which valve spring remover to get. Depending on the type, all four valves on one cylinder can be done at once, or have to do all Intake valves on 1-3-5, then all Exhaust on same engine side. In this case I have to rotate the engine after every pair of valves.
BTW, I've decided to go with the FelPro kit, just like yours. I got it on sale at RockAuto for $21
 
  #9  
Old 09-29-2018, 05:31 AM
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I am about to replace my valve seals as well. Two questions:

First, how hard is it to extract the old ones?
Second, should I consider replacing my lifters while I have things apart? I am at 137,000 miles, and I had some ticking recently but got it to go away by doing the factory recommended procedure of 15 second revving to 2000 rpm ten times to purge air from them.
 
  #10  
Old 09-29-2018, 07:01 AM
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When I removed the valve stem seals, I had the cylinder heads off and the valves removed so I just used pliers, grabbed the seal rocking it and yanked it off. With the valve stem out of the way, I had easy access.

Doing it while the heads are still on and valves in place might be a little more difficult but I think you should still be able to use the pliers technique
https://mitsubishiforum.com/forum/mi...e8/#post314932
 

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