1998 RZJ95 rough idle help (1 Viewer)

[1998prado]

Must have been neglected. I bought a JDM 3RZ-FE which had about 250k kms on, had been badly neglected, dropped a valve or two, repaired by idiots who got so much junk in the engine that all bearing surfaces were scratched. I decided to do a full rebuild, with oversized pistons, new balance shafts, ground the crank, new head and valves. Not cheap but the resuts were worth it.

Before condemning yours, make sure you repeat the measurements, all plugs should be out so the engine can spin over as freely as possible.

But assuming the numbers posted are correct, sorry to hear that.

Yeah I think I’ll probably do the same thing if it comes to that. I’ll try the leak down test asap, I’m hoping it could just be the valves or the gasket, gonna be fun learning to remove this head. Worst case needing a full rebuild is gonna be very expensive for me, I don’t have the capacity to pull the engine myself right now. Thanks for your feedback though, its been very helpful

 

[Eurasiaoverland]

Yeah I think I’ll probably do the same thing if it comes to that. I’ll try the leak down test asap, I’m hoping it could just be the valves or the gasket, gonna be fun learning to remove this head. Worst case needing a full rebuild is gonna be very expensive for me, I don’t have the capacity to pull the engine myself right now. Thanks for your feedback though, its been very helpful

You're welcome, keep posting stuff up. Doing a valve job on the head and a new head gasket shouldn't set you back too much. But the cost escalates if you want to/have to rebuild the bottom end. High oil consumption would be an indication of worn rings and a need to rebuild the bottom end, but this can also come from valve guides. A leak-down test will let you diagnose which one, or both, need repairing.

 

[1998prado]

You're welcome, keep posting stuff up. Doing a valve job on the head and a new head gasket shouldn't set you back too much. But the cost escalates if you want to/have to rebuild the bottom end. High oil consumption would be an indication of worn rings and a need to rebuild the bottom end, but this can also come from valve guides. A leak-down test will let you diagnose which one, or both, need repairing.

Gotcha, well it doesn’t seem to be consuming a lot of oil so hopefully that’s a good sign. I’ll update again after the leak down test.

 

[1998prado]

Update time:
Finally got to doing a leak down test which has led me to believe it is a blown head gasket between cylinders 2 and 3. I decided to buy a new remanufactured head with all new gaskets. Idk if there’s any issues with existing within my current head, but better safe than sorry. If my current head turns out to be good then I’ll just keep it as a back up. The new head is set to arrive tomorrow so I’m hoping to begin work this week. We’re finally getting snow here so I’d really like to have my 4x4 through the winter as much as possible. Wish me luck on this removal/install! Any tips going into this are welcome and appreciated, thanks.

 

[1998prado]

The tear down has officially begun today! I’m fortunate enough to be able to utilize my shop space at work to accomplish this, I’ll be putting in as much time as I can on this each day, optimistically 4-5 hours a day with lunch time and staying after working hours. Hopefully that means it won’t take too many days! Planning to paint my valve cover while I have it off too, excited to get some feedback on it

 

[1998prado]

Managed to get the head off today just before cleaning up and heading home. The gasket looked fine at a glance, but I’ll inspect more closely tomorrow

 

[1998prado]

Less progress today, but managed to clean the pistons and block surface with a scraper and honing stone. Also replaced my thermostat because more and more I’m thinking this was an over heating issue. After inspecting the old head and the old gasket I think the head simply warped, thermostat was sticking so I didn’t know. Also got paint and clear coat on the valve cover! Color reveal!

 

[1998prado]

Wasn’t able to do much this morning, I need to chase the bolt holes on the block but my shop didn’t have the proper size tap. Next week I’ll resume with hopefully nothing to stop me. I got some pictures of the final look of the valve cover after clear coat and curing. Lmk what yall think! I’m pretty happy with how it turned out. Its gonna be really bold in my engine bay!

 

[1998prado]

Quick update:
The tap I need has to be ordered and arrives this Friday, so no head install this week in the meantime I’m going to clean up and paint what I can, including the head! And I’ll be installing some LED headlights too, trying to be productive with this unexpected delay!

 

[Eurasiaoverland]

The head gaslet didn't look obviously blown, but hard to tell from a single picture.

You mention a shop. What have they done? Did they confirm the head was warped and skim it? Have they had the valves out to check the valve seats and margins? Or at least tested the valve seal in the head?

Hopefully they have done these, but if not, I certainly wouldn;t be rebuilding that engine until it was clear what caused the low compression on two adjacent cylinders.

 

[1998prado]

The head gaslet didn't look obviously blown, but hard to tell from a single picture.

You mention a shop. What have they done? Did they confirm the head was warped and skim it? Have they had the valves out to check the valve seats and margins? Or at least tested the valve seal in the head?

Hopefully they have done these, but if not, I certainly wouldn;t be rebuilding that engine until it was clear what caused the low compression on two adjacent cylinders.

The shop only did a compression and leak down test for me, I bought a fully built brand new head to put in it, the old head hasn’t been tested in any way yet.

 

[1998prado]

TODAY WAS FINALLY PRODUCTIVE!!
My tap came in two days earlier than expected, so I was able to chase all the necessary threads and get this head finally on! I got the head, cam shafts, timing chain, chain tensioner, valve cover, exhaust manifold, fuel injectors and lines, intake manifold and throttle body all installed and torqued to factory specs with new gaskets. The finish line is in sight tomorrow I’ll be able to button everything up and hopefully get it started and driving again, I’m doing new coolant and oil as well (managed to spill a s***-ton of oil on the shop floor today lol) I’ll be posting again soon boys

 

[1998prado]

More pics

 

[Eurasiaoverland]

Did you strictly follow the procedure to remove the cam with the small lock bolt, to keep the tension on the spring-tensioned part of the gear? If not, the engine will clatter like a diesel (I speak from experience of making this mistake).

 

[1998prado]

Did you strictly follow the procedure to remove the cam with the small lock bolt, to keep the tension on the spring-tensioned part of the gear? If not, the engine will clatter like a diesel (I speak from experience of making this mistake).

I followed the FSM exactly as it said to do all that, so hopefully I’ll have no issues! I followed it for as much as possible on everything.

 

[Mudder]

It’s looking good!

 

[1998prado]

It’s looking good!

Thanks man! I do think the paint went a long way for this engine bay

 

[1998prado]

Well today was the completion of the reconstruction, however not the end of the work. I believe I have a timing discrepancy, I started it up for the first time and it was idling pretty poorly, I think the issue likely has to do with my distributor. I watched a few videos and did some reading about how to set the distributor back in place correctly, but something sounds off. I’m quite confident that my cams are in proper time with the pistons, I cycled them multiple times while I had the valve cover off, checking the marks. Wondering if its possible that I have my distributor 180 degrees off from the cams? Would it still run with it that far off?.. any ideas or things to check would be appreciated, thanks yall.

 

[1998prado]

Great update time! So I didn’t mention it in my last post, but I had a fuel leak at my injectors (I thought it was a small issue not worth mentioning). I came to realize that I needed injector cushions/isolators, found some locally and installed them today, lo and behold it fixed the poor idle that I assumed was some sort of timing issue! It’s running great! It didn’t seem like it was losing a lot of fuel, but apparently it was making a huge difference. I got everything buttoned up today and drove it home, and later into town and back with no issues! Praise God! Only thing I see is a small coolant leak from one of the hoses under my throttle body, I’m guessing it’s cracked, so I’ll replace it this or next week. I also installed some new LED head lights today. I’ll take some photos tomorrow to post big thanks to everyone who helped me through this repair!

Also lmk, should I continue to post on this thread as I build out the truck?

 

[1998prado]

Not the flexiest lol, but this is the best I can do at my house. Flexy or not, I think Kenji is looking great! Next plans are to finish building a new console lid, repaint the window borders and install new rain guards, maybe some new suspension or tires after that