Got a '97 1.6L that likely needs valve-train work. It has a nasty "buzz" about 2500 RPM from what sounds like cylinder 4. I know these engines must have valve lash adjusted via shims. (I'm used to the traditional feeler-gauge & lock-nut arrangement.) I've called around, and I've found that the local Toyo dealer is the only place that does valve adjustment on these engines. I don't have any problem with most of the engine work, even pulling the head if necessary. However, how much can "really" be done by me twisting the wrench and how much MUST I have the dealer do? In fact, how much will a typical machine shop do as far as new seals, guides, etc.? I'm used to taking a set of V-8 heads to a machine shop, and getting them back with new seats ground, new seals, etc. What is the typical procedure with upper-end mechanical repairs if you want to do as much of the work as you can yourself? I'm praying that I don't find cam lobes pounded flat or something else really expensive.
Do a leakdown test to make sure your engine internals are OK BEFORE you do too much work for nothing. I thought all these engines had hydraulic lash adjusters so thats why they run at basically zero clearance.
I haven't got to doing a leakdown test yet, but I did pull the valve-cover today. I didn't see ANY signs of wear on cam lobes; no visible flattening. Minor surface varnish, no sludge, visibly looks great. I do have have a compression tester, so I at least did that. Surprisingly, even though the mill has almost 120k Miles on it, the compression on all cylinders was between 205 and 208 PSI. I couldn't ask for anything more even. Plugs had been in it for 40k and looked almost new, no soot, no oil, nothing unexpected. Therfore, I'm not really expecting to find anything significant with leakdown test, but I'll do it in a few days to rule it out. If it's leaky, the compression shouldn't be that good, or that balanced. For the umteenth time, I probed around with an engine stethescope, including EGR valve. I couldn't find anything I could identify as a source. The buzzing can be heard with vacuum hose on, and off EGR valve, so I don't expect it is that either.
It is definately NOT exhaust (although it sounds a lot like a loose muffler baffle and only buzzes between 2000-2500 RPM or so). The engine made this same sound before we did a complete exhaust upgrade recently. I was hoping it would go away. We've put on a new S/S header, new cat, new muffler, all new pipe, even new hangers. Unfortunately, the noise still exists without an apparent source. It's real annoying.
I REALLY hope it isn't rod or crank bearings.
Any other suggestions from anyone?
I've got another question that came up today regarding a dash light, but I'll make a separate post on that as soon as I send this.
Got a '97 1.6L that likely needs valve-train work. It has a nasty "buzz" about 2500 RPM from what sounds like cylinder 4. I know these engines must have valve lash adjusted via shims. (I'm used to the traditional feeler-gauge & lock-nut arrangement.) I've called around, and I've found that the local Toyo dealer is the only place that does valve adjustment on these engines. I don't have any problem with most of the engine work, even pulling the head if necessary. However, how much can "really" be done by me twisting the wrench and how much MUST I have the dealer do? In fact, how much will a typical machine shop do as far as new seals, guides, etc.? I'm used to taking a set of V-8 heads to a machine shop, and getting them back with new seats ground, new seals, etc. What is the typical procedure with upper-end mechanical repairs if you want to do as much of the work as you can yourself? I'm praying that I don't find cam lobes pounded flat or something else really expensive.
Valve clearance is not hard on these cars. it involves clearance values, shims and math.
Quote:
Originally Posted by speedy25
Do a leakdown test to make sure your engine internals are OK BEFORE you do too much work for nothing. I thought all these engines had hydraulic lash adjusters so thats why they run at basically zero clearance.
If you need to do the VSS do it with the head on.
-SP
They're not. They use shims, (on later models lifters) for valve clearance adjustment. Toyota did have hydraulic lash adjusters on the 5M-GE (not sure about any other engine). I think they had problems with the adjusters on the engine, since regular oil changes are necessary to keep the little small holes in the adjusters clear to avoid problems. It was easier and cheaper to design/build the engine with adjustable valves.
Not really any math involved. If the clearance is too tight, use the next smaller shim and vice versa. An assembled engine will RARELY need anything more. Now a fresh engine with a valve job might require some of that math.
-SP
The Following User Says Thank You to speedy25 For This Useful Post:
Not really any math involved. If the clearance is too tight, use the next smaller shim and vice versa. An assembled engine will RARELY need anything more. Now a fresh engine with a valve job might require some of that math.
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