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

[veektor]

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.

I've been searching on this extensively, and it appears that valve-piston interference is a possibility, but not an assured occurrence. Kind of makes sense to me that when the damaged belt stops rotating the cams, they settle into the lowest energy position, with no pressure on the valves, therefore preventing actual interference.

I'm still going to run a compression test, and if it shows good numbers, I will follow with leak-down, to be sure. Even if none of the valves got bent, I wonder what other damage occurred due to extreme heat. Perhaps the wiring for CMS (I think that's the right abbreviation for camshaft sensor) got fried? Head could have warped. I replaced the lower TB cover, but others have also noticeably melted at the contact points with the engine. Those are damages I can see, and they tell me the engine got really, really hot.

I have been mentally prepared to swap the engine, so all of this troubleshooting now is about basing that decision on empirical evidence, rather than dealership's half-assed assessment that 'engine is melted'.

 

[cwwfj60]

Don’t write off the crank position sensor either, it correlates with the cam sensors, therefore all 3 come into play with these codes sometimes. Worth checking anyways. I’ve seen sensors take very slight damage from a broken belt before, inspect very closely….also insure the teeth are all straight and intact, I remember that reluctor wheel on the crank pulley being fairly flimsy.

 

[veektor]

Don’t write off the crank position sensor either, it correlates with the cam sensors, therefore all 3 come into play with these codes sometimes. Worth checking anyways. I’ve seen sensors take very slight damage from a broken belt before, inspect very closely….also insure the teeth are all straight and intact, I remember that reluctor wheel on the crank pulley being fairly flimsy.

That's an excellent point. Bad readings at the crankshaft may be a better explanation than both camshaft sensors failing at once. I inspected the angle sensor plate before installing, it didn't show any signs of damage. But seeing how the plastic had melted on the TB cover, it is possible the plastic housings on those sensors had shifted them out of place. Definitely will check that out.

 

[veektor]

Compression test was a good idea. Saved me from going down the sensor rabbit hole. With 3 of the cylinders reading 0psi, I don't need to bother with leak down test. The image is my readings jotted down on cardboard.

I'm going to make some calls to machine shops in town, but I'm leaning towards simply getting the whole engine replaced. I don't have a garage to work in, which makes me highly dependent on the weather to work. I also think getting the heads off with engine still in the vehicle can be a chore. I'll have to decide how much I value my time.

 

[cwwfj60]

Bummer! At least you know for sure what the problem is.

 

[veektor]

Finally mustered the courage and the cash to purchase a replacement engine. I had started disconnecting wires, hoses, and everything else holding the engine in place, hoping that engine delivery would take about one week. Instead the engine showed up overnight.

 

[veektor]

So far the only bolts that broke during removal were from the underbelly covers. Engine mounts, exhaust, and transmission housing bolts have been mostly trouble free. But I can't figure out how to disconnect the two top bolts holding engine to the transmission bell housing. In the attached pictures, I am able to access bolts circled in blue from below, but can't see how to reach the bolts in red. I would appreciate some advice on this. My thoughts before I dive deeper into tearing things down:

• Remove the intake manifold, remove the starter, access bolts from above.
• Remove the center console below the stereo/nav, get access to bolts directly. The flaw here is that I understand the purpose of "firewall", and strongly suspect that removing the console will expose a sheet of steel, rather than allow bolt access.
• Shrink down my hands and reach those bolts from below or from the wheel well. Considering that I had to use impact wrench to loosen some of the bell housing bolts, this prospect doesn't excite me, even if my hands were able to reach in there.

 

[Rednexus]

I have not tried this before....but if it were my GX I would remove the console as indicated and, assuming there is no bolt access, drill two holes thorough the firewall with a hole saw, and remove the bolts.

When you are done, seal them back up with some painted sheet metal, rivets or sheet metal screws, and silicone sealant. No one will ever know .

Overall, how bad has this job been? Seems like it could be an easier way to install headers in a GX, which took me 3 days due to horrible bolt access and rusty fasteners.

 

[veektor]

I have not tried this before....but if it were my GX I would remove the console as indicated and, assuming there is no bolt access, drill two holes thorough the firewall with a hole saw, and remove the bolts.

When you are done, seal them back up with some painted sheet metal, rivets or sheet metal screws, and silicone sealant. No one will ever know .

Overall, how bad has this job been? Seems like it could be an easier way to install headers in a GX, which took me 3 days due to horrible bolt access and rusty fasteners.

All options are on the table at this moment, your suggestion is definitely in the running.

As far as my overall impression of this job, I am mostly happy with Toyota's way of running the wire harness, and the vacuum lines. I labelled many of the connectors, but most of them just fall into right place without much chance for mistakes. I've pulled the engine on Subaru Forester and Volvo S60, and GX has by far been the easiest of all, except for the two bolts in question. Having prior experience with this kind of job is helpful, but so is the extra room in the engine bay. Even with prior experience I don't approach engine removal lightly. A lot of parts to keep track of, and draining fluids. I'll tell you how I feel after I swap the headers to the new engine.

Did you remove the front wheels when you worked on the headers? I'm considering using either jackstands or QuickJack, so I can remove the wheels in the front. That will definitely help with access to the engine mounts, and some of the bell housing bolts.

 

[Rednexus]

Yes, I removed the front wheels, sway bar, and all splash guards. It was still pretty tight and I actually only was able to get in 7/8 nuts in on both sides (one lower bolt on each side was simply not possible to tighten with the motor mounts attached to the block and I could not break them loose, but they have not leaked at all due to the thick flanges and use of a OEM gasket).

Glad to hear it is so easy. I yanked the engine out on my old '00 Forester several times (once for a TOB, then again for head gaskets) and it was a 3 hour job out and 4-5 hour job back in. Knowing that it seems like motor removal is the way to go for headers on a GX and might have been quicker than doing it with the engine in!

If you haven't I would also throw a new starter in this engine. A Denso reman is like $100. It's a pretty crappy job with the engine in the truck, due to how terrible the bolts are to get to on the back of the engine. It also took me a day or two in my '07. The starter is probably pretty easy with the engine still out.

 

[veektor]

I went to GXOR Facebook group to ask the question about two top bolts on bell housing, and sounds like the correct way to remove them is by lowering the transmission. Oof!

Now, this is not an unusual procedure, it was also much easier to remove transmission on Volvo, instead of trying to separate them in the engine bay. But we have the infamous Toyota frame to deal with, so things are decidedly not as easy as factory manual would make you believe. Out of 8 bolts holding the diagonal cross members under transmission only 3 came out without breaking. I now have 5 bolts to drill and extract from the frame. I know my frame could be a lot worse, but 5 friggin bolts to drill out is not a fun detour from an already difficult and time consuming job. I usually spray rusty bolts with PB Blaster ahead of time, but haven't come up with a way to spray inside the frame.

Today I'm going to try lowering the transmission, hopefully that works for disconnecting the last bell housing bolts.

 

[Rednexus]

I went to GXOR Facebook group to ask the question about two top bolts on bell housing, and sounds like the correct way to remove them is by lowering the transmission. Oof!

Now, this is not an unusual procedure, it was also much easier to remove transmission on Volvo, instead of trying to separate them in the engine bay. But we have the infamous Toyota frame to deal with, so things are decidedly not as easy as factory manual would make you believe. Out of 8 bolts holding the diagonal cross members under transmission only 3 came out without breaking. I now have 5 bolts to drill and extract from the frame. I know my frame could be a lot worse, but 5 friggin bolts to drill out is not a fun detour from an already difficult and time consuming job. I usually spray rusty bolts with PB Blaster ahead of time, but haven't come up with a way to spray inside the frame.

Today I'm going to try lowering the transmission, hopefully that works for disconnecting the last bell housing bolts.

Those bolts broke on mine when i pulled that crossmember to install headers. I just welded the crossmember directly to the frame instead. The bolts looked like they would be very difficult to drill out and re-tap.

 

[veektor]

Engine is out, now I am waiting on replacement gaskets and bolts. I'll work on repairing the broken bolts in frame, cleaning up the engine, and put the new timing belt on.

Some of my thoughts about lessons learned during engine removal:

• Exhaust: disconnect the front pipes from headers and from each other, but leave the right pipe attached to the muffler. I misjudged the width of pipe crossing under the transmission, and disconnected the right front pipe from center pipe, instead of separating left pipe from right. That didn't buy me the ability to lower transmission, and I had to cut the bolts to separate at the Y joint. In the attached picture, I circled in red the parts that have to disconnect, and in green the one to leave alone.
• Wire harness: the replacement engine came with a complete harness, but I had the notion of keeping the original in place. It turns out that I would have been better off disconnecting in 6 spots at the transmission, and the 6 connectors behind the glove box. Trying to separate the wire harness from the engine, while in the vehicle, was not worth the effort at all. So many bolts attaching to the engine, EGR pipe, I could have left all of them alone.
• Engine Tilt: someone on FB group mentioned the difficulty of removing engine, as the headers were catching on the firewall, and that they had managed to tilt the rear down by using ratchet straps. I will probably add that when putting the engine back because the load leveler alone doesn't help in this situation. The hooks for hoisting the engine are attached diagonally, but front-rear leveling is what is really needed. This time I removed the left header while engine was hanging on the hoist, which allowed me to maneuver easier, but I don't want to repeat the experience by re-attaching the headers when engine is hanging on the hoist.

 

[veektor]

Well, the latest news is that "new" engine is finally installed, bolted up, wired up, plumbed for antifreeze, and fuel. Took a few crank attempts, but it starts, and runs. Yay! Too bad it is gushing oil from left valve cover.

No need to elaborate every step of this sordid month-long affair, but I will share a few highlights.

I spent one day working on extracting bolts stuck in the frame. Some were compliant with the welding therapy, but a couple of them resisted attempts to weld, and had to be drilled out. Here is my Boltcatcher buddy:

The alternator part of the wiring harness was damaged, and I decided to fix it. I was still expecting the harnesses to be interchangeable, and figured it was easier to leave the harness attached to the engine.

 

[veektor]

The first attempt to install the engine was going well, until I realized the wiring harnesses were not 100% identical between 4Runner and GX470. One silly connector didn't match up in the cluster behind glove box. Upon further inspection I realized it was also missing some connectors on the transmission end. If there was a way to replace the harness with engine in the bay, I couldn't see it, so out the engine went.

All connectors look the same, right? Wrong!

Prepare the patient for neuro surgery!

 

[veektor]

After the harness swap the engine went back in, but for the life of me I could not get the bell housing to mate with the engine. The torque converter seemed to be pressing against the flex plate, and there was no give. I should have realized this was happening sooner, because I've had a similar problem on my Subaru engine pull, years ago. Again, I could not see how I could pull out TC and install it back in without getting the engine completely out. So, out the engine went again. OOF! The worst part of this wasn't the pulling itself. Hitting the AC condenser on the way out punctured a tiny hole, so now I need a new condenser, and another refrigerant recharge. More $$$$.

For future reference, make sure TC didn't get dislodged on removal, and re-seat if necessary.

TC popped out:

TC re-seated into transmission housing:

 

[veektor]

After re-seating the torque converter, the engine re-install went smoothly. My work has kept me busy, so it took me a few short evenings to button things up, make sure all wire harness stays were in place, tightened up, engine mounts, transmission housing bolts, and all other odds and ends. Last night I finally had everything in place to crank the engine, and it started!

Sadly, I see that left side valve cover is gushing oil. Not seeping, but leaking very heavily.

This picture makes it look like there is no valve cover gasket on that side, perhaps that's the reason. I hope this is not a beginning of a whole new rabbit hole , because AC condenser replacement will be enough of a side quest to keep me entertained.