3rz-fe valve clearances

[Schady44]

Alright guys, it's been a while since I posted anything.

The 4Runner (99' base 3rz 4wd) has been a little sluggish for a while now. I would say nearly a year but I don't use it as a daily driver anymore.

Got under the hood today and pulled the valve cover to check the clearances, inspect timing chain and guides, etc.. While intake valves are all within spec but 2.5 of the exhaust valves are too tight to fit my .005" feeler gauge under, and the other 1.5 are in the .008-.009 reading. Before I go any further with adjusting I'm hoping someone can chime in and let me know if I'm in more trouble than I think, or if I should just go ahead with the adjustment. Are those valves burnt and am I looking at a head replacement? Has anyone come across this before?

When this all started happening I had found a burnt catalytic converter and suspected it was because of my slightly dirty Egr valve, which I cleaned and replaced the cat. I haven't checked the new cat yet, but I suspect this may have been the underlying issue that I missed from the get go.

Any help would be much appreciated. I'm very capable to do the adjustment, but would like to know if this is indication that the head needs replacing.

Thanks

 

[Kanoe]

I can't help with your question, sorry.

But I'd like to ask for my benefit and others, what mileage are you at and is it the first time they have been adjusted?

Thanks. I'll keep an eye to see what others think of your question.

 

[Schady44]

I'm about 198k. Very pleased with how clean everything is on the top end. Timing chain and guides are in great shape as well

 

[Scramble]

Alright guys, it's been a while since I posted anything.

The 4Runner (99' base 3rz 4wd) has been a little sluggish for a while now. I would say nearly a year but I don't use it as a daily driver anymore.

Got under the hood today and pulled the valve cover to check the clearances, inspect timing chain and guides, etc.. While intake valves are all within spec but 2.5 of the exhaust valves are too tight to fit my .005" feeler gauge under, and the other 1.5 are in the .008-.009 reading. Before I go any further with adjusting I'm hoping someone can chime in and let me know if I'm in more trouble than I think, or if I should just go ahead with the adjustment. Are those valves burnt and am I looking at a head replacement? Has anyone come across this before?

When this all started happening I had found a burnt catalytic converter and suspected it was because of my slightly dirty Egr valve, which I cleaned and replaced the cat. I haven't checked the new cat yet, but I suspect this may have been the underlying issue that I missed from the get go.

Any help would be much appreciated. I'm very capable to do the adjustment, but would like to know if this is indication that the head needs replacing.

Thanks

How do the valves look? If they don't look burnt then just do the adjustment. Definitely do a search on here, there have been threads on this.

 

[Schady44]

Nothing looks burnt that I can tell. I don't have the heads off to look at everything though. I'll dig around and see what I can find. I'm doubting they are burnt since the engine isn't running rough or misfiring.

 

[KidVermicious]

You can't always see a burnt valve from the top. Run a compression test, and if your numbers come back good you'll know you're good to go ahead with just reshimming the valves. If you have bad compression on the suspect cylinders you'll want to dig a little deeper.

 

[St Runner]

I am also invested in a good answer. My tacoma is just under tolerance on one exhaust valve in cylinder 1 and it is on my to do list. Theoretically I would think that unless there is no tolerance the valve would not start to have issues. Of course random theories have screwed up my life before so it would be good to hear from someone who rebuilds them.

 

[Schady44]

I did some digging per scrambles recommendation and found the following on yotatech from a 3rz in a Tacoma.

http://www.yotatech.com/f2/1998-3rzfe-burnt-exhaust-valves-140030/

I ran a compression check when this all started and everything was good, but will run another this weekend if I get a chance before I go any further. I've had to replace burnt valves on VW's in the past, but they would all have a misfire or rough idle. My runner is only sluggish on acceleration (not misfiring or idling rough),but like St Runner random theories haven't gotten me before. So compression test, then an update from there.

Thanks for the input guys!

 

[Scramble]

I did some digging per scrambles recommendation and found the following on yotatech from a 3rz in a Tacoma.

1998 3RZFE Burnt Exhaust Valves - YotaTech Forums

I ran a compression check when this all started and everything was good, but will run another this weekend if I get a chance before I go any further. I've had to replace burnt valves on VW's in the past, but they would all have a misfire or rough idle. My runner is only sluggish on acceleration (not misfiring or idling rough),but like St Runner random theories haven't gotten me before. So compression test, then an update from there.

Thanks for the input guys!

Please report back here with your findings. The only problem with the 3RZ over the years seems to be head gasket failure. Checking & correcting your valve clearances looks like the best way to prevent that. I'd like to try to figure out after how many miles you should check your valves, 30,000 - 50,000 miles? It's not something I'd like to do every 10,000.

 

[eurasiaoverland]

Sorry to but in but I'm trying to reach sufficient replies on this forum so that I can start my own threads -.-

I've got a 3RZ-FE which I recently pulled out of a truck I bought. Over here in Europe the 3RZ 3rd Gen is a very rare beast, so I just bought whatever I could find. The engine seemed to be running OK, the clearances were all good on the exhaust valves, slightly out on a couple of intake valves, the top end looks clean, but from what I can see in the exhaust ports, the valves look very 'dry'. I'm not used to petrol (gasoline) engines and I'm not sure if this is normal.

The truck had been running on LPG which means no carbon build-up. The exhaust valves look very dry to me, with a touch of white to them. Is this normal? Should they not be a little oily??

The intake valves are slightly oily, though I guess the oil gets sucked in there by the intake vacuum.

I'll be pulling the head in a few weeks, just curious to see if anyone can put my mind at rest. I found a piece of valve stem in the front of the cat, so at some point this engine has dropped a valve. Obviously it has been repaired since, but I'm dreading what I see when Oi take the head off!!

Cheers

 

[davidch]

I have experience with a 2002 2RZ-FE engine and a 2000 3RZ-FE. The 2RZ is in a 2WD Tacoma I purchased new. The 3RZ 4WD is in a 4Runner I purchased with 60k. Both are 5 speeds.

For the Tacoma, I've done all the maintenance. On the 4Runner, I don't believe it had the valves checked/adjusted prior to my doing so at 90k.

The 2RZ, which I checked at 50k, had no change in its valve clearances. Some of the exhaust valves had lost .002 or .003 when I checked & adjusted once it passed 100k. I've checked twice since then, at about 25k intervals. In each case, a few exhaust valves had shrunk clearances a little bit under spec. It now has ~150k.

The 3RZ had one exhaust valve under spec, by .001, at 90k. For that engine, I've checked and adjusted clearances every 25-30k since. Usually, a few exhaust valves were a tad under spec. This engine just crossed 200k.

I've never seen an intake valve lose clearance on either engine.

In various web sites, my experience has matched that of other owners of these engines: clearances hold until about 100k, then adjustments are needed at ~30k intervals. I've now got an egg carton with roughly 40 shims.

I have also checked valve clearances on five 5VZ-FE engines in 4Runners and Tacomas. All had more than 150k. I don't think, though couldn't prove, they'd ever been checked before. In all those valves, intake & exhaust (5 engines x 24 valves = 120 valves) I've seen about 5 valves, intake or exhaust, that needed adjustment, and in all cases the valve was just .001 or .002 under spec. This, too, tracks with the stated experiences of others. A valve clearance under spec by an amount that small is, I think, almost within the bounds of manufacturing variance.

It's my belief, though I cannot prove, that Toyota specified a slightly inferior grade of steel in the exhaust valves, and maybe the valve seats, for the 4-cylinder engines. That's understandable for two reasons: 1) knowing adjustment was much easier, and thus cheaper, on the 4-cylinder engines this mattered less and 2) more importantly, it's necessary for a manufacturer to figure out ways to make a 4-cylinder less costly to build. Save 5 cents/valve on a few million valves and the bean counter has paid for himself. The engine makes it through the warranty period without its valves needing adjustment, and that's what counts.

Fortunately for 2RZ and 3RZ owners it's just the exhaust valves that generally need adjustment, and if you don't want to struggle with the special tools just remove the cam to swap shims. Exhaust cam removal doesn't need to disturb the timing chain and tensioner, as would removing the intake cam. Exhaust cam removal is straightforward, following the FSM, and only a torque wrench is thus needed to adjust the valves.

In my experience, that exhaust valve closest to the firewall cannot be adjusted with special tools by a human with ordinary sized fingers and hands. It would take the patience of Job, and the fingers of a newborn, to do the job. Remove the cam.

To my understanding, as long as clearance doesn't shrink to 0, or very near 0, you won't burn a valve. .004 or .005, though under spec, isn't a cause for worry. Correct it and sleep well.

Finally, when calculating which shim to install, consider going to the high end of the specified clearance. This will add a margin of safety should you let the maintenance intervals go too long.

 

[Scramble]

I have experience with a 2002 2RZ-FE engine and a 2000 3RZ-FE. The 2RZ is in a 2WD Tacoma I purchased new. The 3RZ 4WD is in a 4Runner I purchased with 60k. Both are 5 speeds.

For the Tacoma, I've done all the maintenance. On the 4Runner, I don't believe it had the valves checked/adjusted prior to my doing so at 90k.

The 2RZ, which I checked at 50k, had no change in its valve clearances. Some of the exhaust valves had lost .002 or .003 when I checked & adjusted once it passed 100k. I've checked twice since then, at about 25k intervals. In each case, a few exhaust valves had shrunk clearances a little bit under spec. It now has ~150k.

The 3RZ had one exhaust valve under spec, by .001, at 90k. For that engine, I've checked and adjusted clearances every 25-30k since. Usually, a few exhaust valves were a tad under spec. This engine just crossed 200k.

I've never seen an intake valve lose clearance on either engine.

In various web sites, my experience has matched that of other owners of these engines: clearances hold until about 100k, then adjustments are needed at ~30k intervals. I've now got an egg carton with roughly 40 shims.

I have also checked valve clearances on five 5VZ-FE engines in 4Runners and Tacomas. All had more than 150k. I don't think, though couldn't prove, they'd ever been checked before. In all those valves, intake & exhaust (5 engines x 24 valves = 120 valves) I've seen about 5 valves, intake or exhaust, that needed adjustment, and in all cases the valve was just .001 or .002 under spec. This, too, tracks with the stated experiences of others. A valve clearance under spec by an amount that small is, I think, almost within the bounds of manufacturing variance.

It's my belief, though I cannot prove, that Toyota specified a slightly inferior grade of steel in the exhaust valves, and maybe the valve seats, for the 4-cylinder engines. That's understandable for two reasons: 1) knowing adjustment was much easier, and thus cheaper, on the 4-cylinder engines this mattered less and 2) more importantly, it's necessary for a manufacturer to figure out ways to make a 4-cylinder less costly to build. Save 5 cents/valve on a few million valves and the bean counter has paid for himself. The engine makes it through the warranty period without its valves needing adjustment, and that's what counts.

Fortunately for 2RZ and 3RZ owners it's just the exhaust valves that generally need adjustment, and if you don't want to struggle with the special tools just remove the cam to swap shims. Exhaust cam removal doesn't need to disturb the timing chain and tensioner, as would removing the intake cam. Exhaust cam removal is straightforward, following the FSM, and only a torque wrench is thus needed to adjust the valves.

In my experience, that exhaust valve closest to the firewall cannot be adjusted with special tools by a human with ordinary sized fingers and hands. It would take the patience of Job, and the fingers of a newborn, to do the job. Remove the cam.

To my understanding, as long as clearance doesn't shrink to 0, or very near 0, you won't burn a valve. .004 or .005, though under spec, isn't a cause for worry. Correct it and sleep well.

Finally, when calculating which shim to install, consider going to the high end of the specified clearance. This will add a margin of safety should you let the maintenance intervals go too long.

This is great info, thanks

 

[Schady44]

Absolutely great info. Thanks David. My only concern is that on those 5 valves I can't fit my .005 gauge in (which is the smallest gauge I have). I'll be running a compression test this week to make sure there aren't further issues on those cylinders, and hopefully be doing the adjustment and hitting up the trails by the weekend!

Great info to know about the inspection intervals. I imagine mine are so far out because this is the first check I have done and I'm approaching the 200k mile mark.

 

[gamefreakgc]

Sorry to but in but I'm trying to reach sufficient replies on this forum so that I can start my own threads -.-

I've got a 3RZ-FE which I recently pulled out of a truck I bought. Over here in Europe the 3RZ 3rd Gen is a very rare beast, so I just bought whatever I could find. The engine seemed to be running OK, the clearances were all good on the exhaust valves, slightly out on a couple of intake valves, the top end looks clean, but from what I can see in the exhaust ports, the valves look very 'dry'. I'm not used to petrol (gasoline) engines and I'm not sure if this is normal.

The truck had been running on LPG which means no carbon build-up. The exhaust valves look very dry to me, with a touch of white to them. Is this normal? Should they not be a little oily??

The intake valves are slightly oily, though I guess the oil gets sucked in there by the intake vacuum.

I'll be pulling the head in a few weeks, just curious to see if anyone can put my mind at rest. I found a piece of valve stem in the front of the cat, so at some point this engine has dropped a valve. Obviously it has been repaired since, but I'm dreading what I see when Oi take the head off!!

Cheers

From my experience, the intake and exhaust valves are pretty dry on these engines and that's normal. I just fixed up a 5VZ-FE and the intake valves were actually very dry, had almost no oil or residue at all on them.

The 5VZ-FE rarely needs any kind of valve adjustment. I cracked my current one open at 190k miles and it was in perfect shape.

 

[Schady44]

Quick update. Ran a compression test tonight. All 4 cylinders are averaging 135psi (132-138) and holding. I'm still waiting on the valve adjustment tools to come in, but will just be going forward with the valve adjustment.

 

[Schady44]

Been a while but I adjusted all the exhaust valves. I found a .002" feeler gauge which snuck into he ones that weren't registering. Bottom line. Engines back together and running great. In fact everything was going so good I couldn't stand it so I broke some stuff on the trail last weekend [sarcasm]... So back to the garage for some welding!


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