Engine overheated on '08 GX470, looking for reasonably priced replacement (1 Viewer)

[veektor]

Hi, all. I'm not big on forum introductions, but here we are. I've lurked around here on occasion, didn't feel like I had much to contribute, but now I need all the help I can find.

I suspect there are some folks here who also belong to Facebook's GXOR group. They may recognize me as the guy who recently posted a pic of overheated GX in Colorado, with 4 kayaks on top. FWIW, we had a good vacation, and were returning home, so at least I got that going for me.

I had a Lexus dealership take a look for me, and their diagnosis was "no compression, needs new engine". They did not provide specs on where compression was low, so I plan on doing a compression test of my own. The fact that engine was turning over, but wouldn't start makes this a plausible explanation. Whether compression is lost due to bent valves, burned-through rings, or warped head, is probably irrelevant, because I am not experienced enough to properly rebuild in parts, and my best bet would be to replace the whole assembly. I have pulled engines on a couple of cars before (Subaru Forester and Volvo S60), so I know this is a job I can handle.

The rig is back at my house, now I can take my time with investigating what happened, and perform the repairs at my own pace. I am hopeful to find something simple and easy to fix to get me running, but I am also preparing to swap the engine when nothing less will work.

So far my search has led me to places that want $2500-$4000 for a used engine. I may have to bite that bullet eventually, but I'd rather explore less expensive options first. I know that this forum is attended by enthusiasts, some of whom are mechanics, and may be able to point me in right direction.

I will continue to provide updates on my investigation in this thread. Below is the pic I posted on FB, shortly after the engine stalled.

 

[veektor]

One thing I know for sure: it got really toasty. The overflow hose nipple at the radiator neck melted completely, spraying coolant over the area.

Coolant looks black in overflow tank. Engine oil looks clear on the dipstick, no milkshake, making me hopeful that coolant may not have mixed into oil. The smell of oil is definitely bad, I would describe it as burned rubber.

Including some more pics to make the boring story a little more interesting.

 

[newdoc]

This happened on a 2007 Tundra of mine with the 4.7. Son tried to limp it home 30 miles after overheating and likely further messed up head gasket and partially melted the stupid plastic intake. Replacing the head was just as expensive and more problematic than a sourced a rebuilt engine from Engine World which had a 4.7 that looked brand new. After a new intake (no used available) and most of the external parts from the old engine, new fluids and plugs had me on the road again. I did a new timing belt and water pump just to be sure. Engine World was easy to deal with. Luckily I have family with an auto shop to compete the work or it wouldn't have been worth it to me on that particular pickup.

2005-2009 Lexus GX470 4.7L Used Engine | Engine World - https://www.engineworld.com/product/2005-2009-lexus-gx470-4-7l-used-enigne/

 

[veektor]

This happened on a 2007 Tundra of mine with the 4.7. Son tried to limp it home 30 miles after overheating and likely further messed up head gasket and partially melted the stupid plastic intake. Replacing the head was just as expensive and more problematic than a sourced a rebuilt engine from Engine World which had a 4.7 that looked brand new. After a new intake (no used available) and most of the external parts from the old engine, new fluids and plugs had me on the road again. I did a new timing belt and water pump just to be sure. Engine World was easy to deal with. Luckily I have family with an auto shop to compete the work or it wouldn't have been worth it to me on that particular pickup.

2005-2009 Lexus GX470 4.7L Used Engine | Engine World - https://www.engineworld.com/product/2005-2009-lexus-gx470-4-7l-used-enigne/

Looks like Engine World price is $2100. Not bad. Thanks for the link!

Your story makes me wonder what really happened with my rig. I don't see any signs of plastics melting on the engine itself, only the radiator plastic. My wife keeps asking how this is possible, since engine still 'looks pretty clean'. I'm going to keep methodically investigating, and should have some compression numbers later today.

Here is what I remember happening. On the way to Western Colorado, we stopped to visit family in Windsor (near Fort Collins). When we were leaving Windsor, my EML came on, and I immediately regretted leaving my OBDII scanner at home. We stopped by AutoZone to borrow their reader, and came up with P0333 code "Knock Sensor 2 Circuit High Input (Bank 2)". Since I know that I specifically chose Premium gas on this trip, I figured not a big deal, shouldn't be knocking anyway, probably loose connection, or faulty sensor. Drove carefully into the mountains, and at the Georgetown rest stop the EML went away, like magic. Okie dokie!

We spent a week in Glenwood Springs area without any warning lights, then headed back to Kansas. Made a stop for gas in Georgetown again, and the EML came back on. Weird coincidence, but OK, I figured I know what the issue was before, probably the same sensor, right? It was probably twenty minute later that I started to notice the valves sounding very 'pingy', and losing power. Very shortly after the engine stalled, as I was pulling over to the shoulder. There was strong smell of coolant, and steam coming under the hood. I let it cool off a little, then tried starting again, without success. Crank, no start.

At this time my son, who apparently had his OBDII scanner all along, rolled up to see what was happening. I read the codes again, got the same P0333, but also P0117 "Engine Coolant Temperature Sensor 1 Circuit Low". Seemed logical, considering the coolant spewing everywhere. Now, people have been asking when I noticed that engine was overheating, and I honestly did not see it happening. With several warning lights that come on with EML, and being on high alert in the mountains, I honestly can't say if I simply didn't notice high temp warning light, or if it never actually came on.

So, this is the story as I remember it.

 

[veektor]

Tested compression last night. Didn't do it on all 8 cylinders, only the 5 that were easier to access. Got 0psi (yes, zero, zilch, nada) on 4 of them, 40psi on one.

Because I just bought this compression test gauge, I connected to the known running car, Lexus ES330. Reading 150psi off the bat. Conclusion? My GX470 engine is completely toast. Time to place order with Engine World, I suppose.

 

[Rednexus]

Sorry to hear about the toasted 2UZ! Please post pics/info on the engine R&R, if you are able to. I have not seen a lot of info on people who have actually pulled one of these engines from a GX. I spent 3 days putting long-tube headers on mine and think it would have been easier to just yank the motor out with how tight the heads are to the frame, so it would be good to have a writeup/thread on engine replacement.

 

[cwwfj60]

Tested compression last night. Didn't do it on all 8 cylinders, only the 5 that were easier to access. Got 0psi (yes, zero, zilch, nada) on 4 of them, 40psi on one.

Because I just bought this compression test gauge, I connected to the known running car, Lexus ES330. Reading 150psi off the bat. Conclusion? My GX470 engine is completely toast. Time to place order with Engine World, I suppose.

Have you verified your timing belt is intact? Just a sneaking suspicion based on your compression test results....

with the overheat you are likely facing other factors, but thought I’d throw that out there.

 

[veektor]

Have you verified your timing belt is intact? Just a sneaking suspicion based on your compression test results....

with the overheat you are likely facing other factors, but thought I’d throw that out there.

I have not opened the covers to look at TB yet. The idea crossed my mind, but I wonder if that changes anything for me. If TB shredded as engine was overheating, then my valves are probably still bent, requiring at least a head job.

But if it turns out that TB is indeed broken, it could be worth the try to replace, and measure compression again. Maybe by some miracle I avoided valve damage?

One thing will keep bugging me as I tear into this engine: what, if any, was the significance of P0333 code for knock sensor. Was it pure coincidence? Did the sensor go bad because engine was running too hot? Did ECU retard the timing because of faulting knock sensor, and cause engine to run hotter? Will I ever know?

 

[veektor]

Have you verified your timing belt is intact? Just a sneaking suspicion based on your compression test results....

with the overheat you are likely facing other factors, but thought I’d throw that out there.

OK, you called it! Timing belt is indeed gone. I opened one of the covers, noticed it felt rather loose. I turned the crank a couple of times, no movement on TB or the cam sprocket at all. I will get a new TB kit, and check compression afterwards.

Just for the record, I used the Aisin TB kit TKT021 (no longer available at RockAuto) last year when I was replacing the radiator. I had the impression that kit components were good quality. TB, WP, and idler are only one year /10K miles old. I hope to find more clues once I remove the radiator and TB covers.

 

[cwwfj60]

So my thought process before I knew the belt was gone.....if you lost a tooth or two on the belt, it could cause knocking on a out of time motor, knock sensor code, continued driving on a knocking engine could overheat it, all about the time the motor shut down when the belt finally gave out completely.

Being that the water pump is on the t-belt, perhaps there is a chicken or egg scenario here...? Water pump locked up and killed the belt even.....maybe.

That aisin kit is good, used dozens of them, although I don't buy them from RockAuto myself. I hope your parts weren't the problem.

 

[sedonut]

If it were me, I would be inclined to not start the engine until I was sure no valves were bent. Caution might indicate pulling the heads or getting an inspection camera in there to take a look. If you only slightly bent a couple of valves, your lower end might still be fine. A valve job is cheaper than a whole engine. Granted there is a lot of labor to remove and replace the heads.

 

[Rednexus]

I had a belt break on my Subaru EJ25. It was a supposed OEM belt I bought on eBay that was a knockoff. Did you actually get the Aisin kit from RockAuto or from somewhere else (Amazon, eBay?). If you got it somewhere else it might have been a fake.

You can check for valve damage by pulling the sparkplugs and putting a cheapie Harbor Freight borescope into the spark plug holes. If the valves hit the pistons (99.9% chance the did), you'll see little fingernail-like indentations in the pistons from where they hit. For my EJ25 Subaru, I bent all 16 of the valves, but none of them badly, and none of the pistons were damaged besides the tiny indentations. I bought 16 new valves, lapped them, and put the engine back together and it's still running just fine a year later. However, a SOHC Subaru is very easy to work on and adjust the valve lash, which I understand is not the case with a 2UZ (shim and bucket last adjustment).

I'd recommend checking for the valve/piston interference as mentioned above, then getting a quote from a machine shop to rebuild the heads with all new valves. I think with your labor to R&R the engine (replacing the heads with the engine in the vehicle will NOT be fun or maybe even possible) that it will be a wash or easier to just put in a good used motor, if you can find one.

 

[veektor]

I took some pictures of the piston tops with a boroscope yesterday. Getting the camera down spark plug hole was more difficult than I expected, because there is no taper on either the hole, nor the camera tip. Because of that my pictures are not in a specific order of cylinders, and didn't capture as wide as I wanted. That said, I did not see anything resembling a ping mark on the piston top.

I will go back and attempt another scope session, and try to get wider view, as well as organize the pics a little better. Including the pics here from yesterday. If anything jumps out at anyone, please point it out to me.

 

[cwwfj60]

Have you torn down the covers to check for damage?

Pistons look fine based on the pics.

I’d be slapping a new belt on there and seeing what happens. You still have other issues to worry about, but if your motor runs then this is a repair scenario and not a replacement.

I would be interested to see if any of the pulleys are locking up.

 

[veektor]

Have you torn down the covers to check for damage?

Pistons look fine based on the pics.

I’d be slapping a new belt on there and seeing what happens. You still have other issues to worry about, but if your motor runs then this is a repair scenario and not a replacement.

I would be interested to see if any of the pulleys are locking up.

Finally got all the covers removed. Belt is shredded, as expected. My bet on root cause is the No. 2 orange tension pulley. It was slightly wobbling on the bolt, which must have come loose with vibration. When I was replacing the timing belt last year, I remember looking up the torque specs for the bolts, but maybe this one slipped by, as I was working in intense heat outside. Strongly considering using loctite this time. The waterpump looks fine, but I'm getting a complete TB+WP kit again, so I'll swap it for a good measure.

 

[veektor]

Here are the parts I have on order right now. I will have to add the lower TB cover (over the crankshaft) because it had melted a little. I'd like to hear some thoughts on adding or removing items on this list.

 

[veektor]

Have you torn down the covers to check for damage?

Pistons look fine based on the pics.

I’d be slapping a new belt on there and seeing what happens. You still have other issues to worry about, but if your motor runs then this is a repair scenario and not a replacement.

I would be interested to see if any of the pulleys are locking up.

Finally got all the covers removed. Belt is shredded, as expected. My bet on root cause is the No. 2 tension pulley. It was slightly wobbling on the bolt, which must have come loose with vibration. I may not have torqued it properly when installing timing belt a year ago, and strongly considering using loctite this time.

 

[veektor]

New timing belt, waterpump, radiator, and hoses are installed. Buttoned everything up, reconnected the battery. Engine turns over, but fails to start. OBDII scan reports camshaft position sensor codes P0340 and P0345.

Today is raining, so I won't be digging around under the hood. Instead I get to think through my next move.

Obviously I need to verify that camshaft position sensors are properly connected. Given that they are not a cheap part, I'm planning to run compression test on all cylinders before I throw more $$ and parts at this engine.

The screenshot is showing them "pending" because I had cleared the codes after the first try, and they appeared again.

 

[Rednexus]

If the cam sensors end up being OK, another option to check for valve damage would be to set a piston at TDC and apply compressed air in through the spark plug hole using a leakdown tester. You'll then hear it escaping through the intake or the exhaust if you do indeed have valve damage (or though the crankcase if it is something worse....). I'm extremely surprised you didn't see valve damage with the borescope being that the 2UZ is an interference engine....but perhaps you got very, very lucky. When this happened to my old Subie it just died and there was no noise or "impact" to be felt.

 

[veektor]

Found some more info from what appears to be an official Toyota publication for troubleshooting 2UZ-FE. I know that the battery was allowed to sit completely drained for a couple of weeks before I got the rig home. Battery has been in the garage on trickle charger since then. When engine was cranking last night, it sounded rather strained, so next time I'll have the charger-booster on the battery as I crank, to ensure good voltage (over 11V) when starter is engaged. I know that ECU expects good voltage, and weird things happen when voltage is low. Also, low hanging fruit.