3VZE with low vac, rough idle, and strange noise
11-16-2015, 01:54 PM
#23
Registered User
Thread Starter
Join Date: Jan 2015
Location: Las Vegas
Posts: 10
Likes: 0
Received 0 Likes
on
0 Posts
Hello Everyone, sorry for the delay, but I may have a solution for you. Here's what worked on my 3VZE to fix the idle issues: Tight Valves.
Being that this is a motorhome I just bought, I wanted to go through anything that could cause problems down the road. Knowing that the valve setup on the 3VZE is crucial, and could even cause my idle problems, I started tearing the top of the motor down. Pull upper intake plenum, valve covers, cams, etc. I found that half of the valves, all exhaust or intake (can't recall which side), were off by about the same .010-.020. as I recall. Can't remember exactly, it was a few months ago..
The valves are adjusted with special shims between the cam lobes and valve buckets. You want to get the clearance between the lobe and shim just right. Follow manual spec and triple check with a clean set of feeler gauges. You will need a shim kit (or a clairvoyant to help you order only the sizes you'll need), proper tools and PATIENCE. There is a shim tool out there to help change shims without pulling the cams. Like most internal engine parts, fit and condition is paramount.
**The shims are Case Hardened, DO NOT grind them to fit for two reasons: 1) You will grind off the hardened surface and they will be useless. 2) You most likely don't have the means to grind them PERFECTLY flat and parallel.
Why the valve clearance is important and caused my idle problem...
Valves clearances too tight: Poor valve seal causing rough idle as above, and a host of other performance issues if bad enough. More importantly, the valve gets lack of seat time and pressure to properly dissipate the heat into the head casting. Next stop, burnt valves and head rebuild.
Valve clearance too loose: Excessive valve chatter or noise, damage to mating surfaces of valve train. Poor performance from valve not opening enough and/or wrong valve timing if bad enough. The 3VZE may have a little healthy chatter when warmed up, but not excessive.
Valves a little too loose may actually be better than too tight. A little chatter vs risk of burnt valve in my opinion.
At 55k miles, this truck had the head gasket recall service performed at a Toyota dealer in El Cajon, CA. I suspect that they mixed or carelessly reinstalled the valve shims putting the valve train back together. I can't remember whether it was Exh or Int valves, but it was all one or the other. And off by the same amount. I think about .010-.020 of error in valve clearance, but I can't remember now. And I wasn't surprised, judging by the fact that it looked like they scraped related gaskets with a flathead screwdriver...
Anyway, I got the shims right, buttoned it up and BAM! It purrs like a kitten. Drives like new. With at least a quieter strange noise in the intake. This seems to have solved 95% of my concerns. Vacuum went up a bit to what I feel is acceptable at my elevation. Also completely gone, is the chugging or pulsing feeling in the chassis when braking to a slow stop. Some others have complained about this symptom as well. The poor idle was actually feeding back through the chassis during mild braking. And, I went on a 6000mi month long road trip across the country to celebrate
Not a single hiccup along the way. 3VZE FTW.
Being that this is a motorhome I just bought, I wanted to go through anything that could cause problems down the road. Knowing that the valve setup on the 3VZE is crucial, and could even cause my idle problems, I started tearing the top of the motor down. Pull upper intake plenum, valve covers, cams, etc. I found that half of the valves, all exhaust or intake (can't recall which side), were off by about the same .010-.020. as I recall. Can't remember exactly, it was a few months ago..
The valves are adjusted with special shims between the cam lobes and valve buckets. You want to get the clearance between the lobe and shim just right. Follow manual spec and triple check with a clean set of feeler gauges. You will need a shim kit (or a clairvoyant to help you order only the sizes you'll need), proper tools and PATIENCE. There is a shim tool out there to help change shims without pulling the cams. Like most internal engine parts, fit and condition is paramount.
**The shims are Case Hardened, DO NOT grind them to fit for two reasons: 1) You will grind off the hardened surface and they will be useless. 2) You most likely don't have the means to grind them PERFECTLY flat and parallel.
Why the valve clearance is important and caused my idle problem...
Valves clearances too tight: Poor valve seal causing rough idle as above, and a host of other performance issues if bad enough. More importantly, the valve gets lack of seat time and pressure to properly dissipate the heat into the head casting. Next stop, burnt valves and head rebuild.
Valve clearance too loose: Excessive valve chatter or noise, damage to mating surfaces of valve train. Poor performance from valve not opening enough and/or wrong valve timing if bad enough. The 3VZE may have a little healthy chatter when warmed up, but not excessive.
Valves a little too loose may actually be better than too tight. A little chatter vs risk of burnt valve in my opinion.
At 55k miles, this truck had the head gasket recall service performed at a Toyota dealer in El Cajon, CA. I suspect that they mixed or carelessly reinstalled the valve shims putting the valve train back together. I can't remember whether it was Exh or Int valves, but it was all one or the other. And off by the same amount. I think about .010-.020 of error in valve clearance, but I can't remember now. And I wasn't surprised, judging by the fact that it looked like they scraped related gaskets with a flathead screwdriver...
Anyway, I got the shims right, buttoned it up and BAM! It purrs like a kitten. Drives like new. With at least a quieter strange noise in the intake. This seems to have solved 95% of my concerns. Vacuum went up a bit to what I feel is acceptable at my elevation. Also completely gone, is the chugging or pulsing feeling in the chassis when braking to a slow stop. Some others have complained about this symptom as well. The poor idle was actually feeding back through the chassis during mild braking. And, I went on a 6000mi month long road trip across the country to celebrate
Not a single hiccup along the way. 3VZE FTW.
11-16-2015, 02:41 PM
#24
Thanks for the info!
Kinda hoping I don't have to go through this though
I came across your thread last night searching about my low vacuum problem (14" is as best it can get at idle).
You say "at your elevation" - do you mean that with altitude vacuum doesn't get as good as it would at sea level? I'm living at ~ 6,000 ft.
Kinda hoping I don't have to go through this though
I came across your thread last night searching about my low vacuum problem (14" is as best it can get at idle).
You say "at your elevation" - do you mean that with altitude vacuum doesn't get as good as it would at sea level? I'm living at ~ 6,000 ft.
11-16-2015, 02:47 PM
#25
Registered User
Thread Starter
Join Date: Jan 2015
Location: Las Vegas
Posts: 10
Likes: 0
Received 0 Likes
on
0 Posts
Yes, vacuum will decrease at about inch of mercury per 1000ft of altitude. Air becomes less dense as you get higher. I'm at about 2200ft above sea level, and that seemed to be accurate when compared to gauge readings while sitting in a Michigan driveway at near
sea level.
sea level.
Thread
Thread Starter
Forum
Replies
Last Post
Seattle_Sign_Guy
95.5-2004 Tacomas & 96-2002 4Runners
0
07-12-2015 12:38 PM
