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Isuzu Trooper 2000, 3.5V6
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Discussion Starter · #1 ·
Hello,

I started adjusting the valve clearances in my Isuzu Trooper 6VE1 (3.5V6) engine. It turned out that I have too large clearance on (almost) all valves, so I have to replace the shims for wider ones. But it is not clear to me, how does valve clearance increase over time? In general, I have about 0.05mm/0.002inch too wide clearance (in relation to the upper limit of the standard in the manual), and the shims are barely worn. The cams look OK too, although I haven't measured them yet, but they don't have any visible abrasions. I would expect a clearance do decrease as the valve seats wear down, instead of increase - do you have any ideas?

Thanks!
Nathan
 

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The shim wears due to friction, remove the shim , flip it over and put it back in. Recheck the clearance.
 

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Discussion Starter · #3 ·
The shim wears due to friction, remove the shim , flip it over and put it back in. Recheck the clearance.
Thanks for the advice, but unfortunately it didn't solve the problem. In general the clearance is ca. 0.05 mm wider than the upper limit (according to the manual), so flipping the shim over doesn't do the job (I tried). And my biggest concern is how it is possible that the clearance increased instead of decrease over time.
 

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Discussion Starter · #5 ·
Are all the valves out of spec or just intakes or just exhaust. Is one bank worse than the other?
Thanks!
  • Left bank:
    • IN: 3 ok, 3 valves exactly at the upper margin (0,33 mm)
    • EX: 5 valves out of spec, 1 exactly at the upper margin (0,35 mm)
  • Right bank:
    • IN: 6 valves out of spec
    • EX: 6 valves out of spec
 

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The cam lobes wear, the shims wear, carbon build up on the valves and seats, adjusted wrong at assembly, adjusted wrong by previous owner. Lots of possibilities.
 

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Been watching this thread. Have to ask: How many miles on it? Have you checked them before? How does / has it been running? What caused check of clearances, just checking? I would say if high mileage, you might want to pull one or more of the cam bearing caps and check for wear or slop on those. Dennis
 

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Discussion Starter · #8 ·
The cam lobes wear, the shims wear, carbon build up on the valves and seats, adjusted wrong at assembly, adjusted wrong by previous owner. Lots of possibilities.
Actually, I thought about all possible causes you mentioned and my thoughts are:
1) cam lobes wear: Cam lobe should wear at the tip much more than at the bottom, as the shim pressures the tip of the lobe, when the valve opens. However, you measure the clearance, when the valve is closed. So, even if the lobe is significantly worn down, the clearance measurement should remain OK-ish. (But the valve opening would be obviously decreased.)
2) the shims wear: I checked, and the shims don't show any significant wear.
3) carbon build up on the valves and seats: That might be a valid reason, but rather for exhaust valves. Is carbon build up expected on intake valves/seats?
4) adjusted wrong at assembly, adjusted wrong by previous owner: This is the last possibility, that I will land with, if I exclude all other possibilities. I don't want to conclude that it was the wrong adjustment, only because I am too incompetent to find a right answer.


Been watching this thread. Have to ask: How many miles on it? Have you checked them before? How does / has it been running? What caused check of clearances, just checking? I would say if high mileage, you might want to pull one or more of the cam bearing caps and check for wear or slop on those. Dennis
  • around 190k miles
  • I bought the car ca 6 months ago, so I didn't check the valves before.
  • The car is running fine, but there is a rather annoying ticking noise. 3.5 engine sounds like a diesel.

Cheers!
Natan
 

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Actually, I thought about all possible causes you mentioned and my thoughts are:
1) cam lobes wear: Cam lobe should wear at the tip much more than at the bottom, as the shim pressures the tip of the lobe, when the valve opens. However, you measure the clearance, when the valve is closed. So, even if the lobe is significantly worn down, the clearance measurement should remain OK-ish. (But the valve opening would be obviously decreased.)
2) the shims wear: I checked, and the shims don't show any significant wear.
3) carbon build up on the valves and seats: That might be a valid reason, but rather for exhaust valves. Is carbon build up expected on intake valves/seats?
4) adjusted wrong at assembly, adjusted wrong by previous owner: This is the last possibility, that I will land with, if I exclude all other possibilities. I don't want to conclude that it was the wrong adjustment, only because I am too incompetent to find a right answer.




  • around 190k miles
  • I bought the car ca 6 months ago, so I didn't check the valves before.
  • The car is running fine, but there is a rather annoying ticking noise. 3.5 engine sounds like a diesel.

Cheers!
Natan
I'm going to guess that it was set up loose by the previous owner or their mechanic. Old school thought was "a loose valve is a happy valve". This goes back to the days of mechanical lifters and many preferred to have them slightly over specs than tight.
If it runs fine, enjoy it. Note that there are many complaints about the V-6s ticking. Dennis
 
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