turbocharged 3B failure/high EGT's/Abuse? (1 Viewer)

[robmobile73]

That's a very generous offer and I really appreciate it and may take you up on it. Squirters definately have to be removed. Trying not to pull and disassemble this engine more than I have to. I ran my hand down the bore to see if the bottom of the liners have any Lip not covered up by cast iron. They do, but it's really thin. Very little purchase for any removal tool.

I got a hone today and am going to see what #3 looks like after I hone it. If the scratches pretty much hone out I"m going to run with it. ....#2 had 480PSI compression with a broken 2cnd ring and scarred up piston crown. The other 2 were 410psi. Pretty darn good given the condition.

Putting in new liners without boring honing after may be problematic as the manual states you must bore and hone after installing them which indicates to me that they are thin and can deform slightly on install due to condition of block hugging liners.

 

[robmobile73]

Could there be a valve problem that mostly cut air-flow in or out of that cylinder? Something caused a local overheat and it's just the one. 700C pre-turbo doesn't hurt anything if it's a true measurement and all cylinders are even. But if you had one at 950C and the others at 500C you'd have a problem and not pick it.

Valves go up and down like they are supposed to and lash was set correctly. I didn't check the intake manifold runners for obstruction, but the head is clear.

All of the pistons have some erosion of the crown edge between the valves. Only 1 piston is mostly undamaged.

The ring sticking is most likely due to Heat/boost + Damage to the piston crown from previous overheat swallowing of a valve seal. (yes the piston crown was dinged up but not punctured. I smoothed it out and hoped for the best. No intention to turbo at that point. So I wasn't too worried). Not sure why I have a broken 2cnd ring on 3 cylinders? The only thing I can think of is they cracked during previous overheat. This is also at least the 3rd head on this engine and there is no telling how many times it overheated before I got it.

Based on what has happened I may try to get some more durable piston rings if possible. I'm guessing the factory rings are regular iron rings. Like to get some Chromemoley rings, or maybe the tool steel rings like you can get for high boost application from Sealed Power. Have to research a bit more. I at least need to figure out what my replacement rings will be made of so I can final hone with the right grit.

 

[robmobile73]

View attachment 2373446

Double thanks for posting this. I just spent 20 minutes searching my manual back and forth looking for this page, but it simply is not in my manual. Page EM76 in my manual is completely different and the "marks are not on my engine block". There is a very faint #2 stamped lightly on one of my pistons though. Good luck with your current issues.

 

[Dougal]

Valves go up and down like they are supposed to and lash was set correctly. I didn't check the intake manifold runners for obstruction, but the head is clear.

All of the pistons have some erosion of the crown edge between the valves. Only 1 piston is mostly undamaged.

The ring sticking is most likely due to Heat/boost + Damage to the piston crown from previous overheat swallowing of a valve seal. (yes the piston crown was dinged up but not punctured. I smoothed it out and hoped for the best. No intention to turbo at that point. So I wasn't too worried). Not sure why I have a broken 2cnd ring on 3 cylinders? The only thing I can think of is they cracked during previous overheat. This is also at least the 3rd head on this engine and there is no telling how many times it overheated before I got it.

Based on what has happened I may try to get some more durable piston rings if possible. I'm guessing the factory rings are regular iron rings. Like to get some Chromemoley rings, or maybe the tool steel rings like you can get for high boost application from Sealed Power. Have to research a bit more. I at least need to figure out what my replacement rings will be made of so I can final hone with the right grit.

What do you think the ring-gap was?

Turbocharged engines have bigger ring-gap as the cylinders run hotter and the rings expand more. With insufficient gap the ends can meet and then they scuff the bore (and break). Middle cylinders can run hotter depending on coolant, air and exhaust flows.

I have seen this on a tractor engine that was turbocharged.

 

[robmobile73]

What do you think the ring-gap was?

Turbocharged engines have bigger ring-gap as the cylinders run hotter and the rings expand more. With insufficient gap the ends can meet and then they scuff the bore (and break). Middle cylinders can run hotter depending on coolant, air and exhaust flows.

I have seen this on a tractor engine that was turbocharged.

I have no clue what the ring gap was. I only suspect that the engine overheated on more than one occasion. If you know how much greater a turbo engine ring gap should be than a NA ring let me know I may file fit the new rings. Common ring sets available are NPR, TP, RIK, and of course the factory Toyota rings(not sure who makes them for Toyota). NPR is the cheapest. Some say RIK is the best. Reading up tonight RIK and NPR seem to be Chrome rings. I don't really know what is best.

Of interesting note, my turbo is a TD04 and it spools up quick and has good power. People say that the CT26 is really too big and is laggy. It could be that my TD04 restricts the exhaust a bit and holds in heat. While it does spool quick and provide better boost at lower throttle/rpm, once at higher RPM high load(highway) it may be restricting flow holding heat. A bigger turbo may be lagging at lower speeds and lower throttle, but on the highway under heavy load it is making more boost/flowing more air and EGT's cooler when it matters most for durability. It is possible that by moving to a TD05 I would loose some low RPM performance, off road performance, and around town, but on the highway it might improve.

 

[Dougal]

I have no clue what the ring gap was. I only suspect that the engine overheated on more than one occasion. If you know how much greater a turbo engine ring gap should be than a NA ring let me know I may file fit the new rings. Common ring sets available are NPR, TP, RIK, and of course the factory Toyota rings(not sure who makes them for Toyota). NPR is the cheapest. Some say RIK is the best. Reading up tonight RIK and NPR seem to be Chrome rings. I don't really know what is best.

Of interesting note, my turbo is a TD04 and it spools up quick and has good power. People say that the CT26 is really too big and is laggy. It could be that my TD04 restricts the exhaust a bit and holds in heat. While it does spool quick and provide better boost at lower throttle/rpm, once at higher RPM high load(highway) it may be restricting flow holding heat. A bigger turbo may be lagging at lower speeds and lower throttle, but on the highway under heavy load it is making more boost/flowing more air and EGT's cooler when it matters most for durability. It is possible that by moving to a TD05 I would loose some low RPM performance, off road performance, and around town, but on the highway it might improve.

Ring-Gap for the Isuzu 4BD1T/4BD2T (102mm bore) is 0.2-0.45mm. My piston rings have always been on the upper end of that tolerance (bigger gap). Ring material needs matched to bore material and there are huge differences in friction (and fuel economy).
The Perkins engine that had issues with ring-gap (91mm bore) has a specified gap of 0.23-0.33mm.
3B manual says 0.3-0.6mm: Inspect Piston Ring End Gap; Check Piston Pin Fit; Inspect Connecting Rods - Toyota 3b Repair Manual [Page 89] | ManualsLib

A small turbo doesn't cause meltdown. It actually provides more cooling air. Exhaust restriction stories are myths.

 

[OGBeno]

Good stuff here @Dougal ... good learning.

 

[robmobile73]

Ring-Gap for the Isuzu 4BD1T/4BD2T (102mm bore) is 0.2-0.45mm. My piston rings have always been on the upper end of that tolerance (bigger gap). Ring material needs matched to bore material and there are huge differences in friction (and fuel economy).
The Perkins engine that had issues with ring-gap (91mm bore) has a specified gap of 0.23-0.33mm.
3B manual says 0.3-0.6mm: Inspect Piston Ring End Gap; Check Piston Pin Fit; Inspect Connecting Rods - Toyota 3b Repair Manual [Page 89] | ManualsLib

A small turbo doesn't cause meltdown. It actually provides more cooling air. Exhaust restriction stories are myths.
[/QUOTE
Thankyou for the information on the ring gap. Learning alot with all this. Not sure about the exhaust restriction quote. I assume you are saying that a smaller turbo doesn't restrict exhaust flow, or if it does it doesn't increase EGT's.

Any opinion on rings and brands: OEM toyota vs NPR vs TP vs RIK? OEM Toyota is 2X more expensive, but that doesn't necessarily make them better. NPR is the cheapest, but that doesn't necessarily make it bad.

 

[robmobile73]

Ring-Gap for the Isuzu 4BD1T/4BD2T (102mm bore) is 0.2-0.45mm. My piston rings have always been on the upper end of that tolerance (bigger gap). Ring material needs matched to bore material and there are huge differences in friction (and fuel economy).
The Perkins engine that had issues with ring-gap (91mm bore) has a specified gap of 0.23-0.33mm.
3B manual says 0.3-0.6mm: Inspect Piston Ring End Gap; Check Piston Pin Fit; Inspect Connecting Rods - Toyota 3b Repair Manual [Page 89] | ManualsLib

A small turbo doesn't cause meltdown. It actually provides more cooling air. Exhaust restriction stories are myths.

Also really appreciate the manual posts from everyone. I've downloaded a couple 3B manuals and sometimes information is straight up not in there, but another "version" of the manual will have the information.

 

[Dougal]

ring opinions

I don't have any experience with toyota rings. Toyota won't make their own either. I once used aftermarket chrome rings on aftermarket chrome liners and they all got eaten to the point of being undrivable in 27,000km. Isuzu use hard chrome liners with a chromed top ring and cast-iron others. Made by Mahle-Izumi.

My opinion is to keep ring materials and bore materials different to prevent adhesive wear. Ring tension affects friction, wear and fuel economy but hasn't got that big an effect on sealing.

 

[robmobile73]

Lot of work with the hone on #3 yesterday. It is smoothed out nicely. All bores are smaller than maximum limit for STD according to the manual. #3 is .002-.004" larger now the others due to work with the hone to remove scoring, but it is still less than the max limit.

I am considering buying a 4oz sample of Cerakote V piston coat heat reflective ceramic coating and coating the tops of the new pistons with it.

I'm doing this without pulling the engine so chances are I won't be able to get everything as perfectly clean as if a machine shop was doing it. Thinking on initial running/break in I should change the oil and filter after the initial 15 minutes or so of running. Then again after perhaps 500Miles.

I've heard a wide variety of initial break in oil change intervals for various different engines. If anyone has an opinion on that for my circumstances please chime in.

 

[robmobile73]

I don't have any experience with toyota rings. Toyota won't make their own either. I once used aftermarket chrome rings on aftermarket chrome liners and they all got eaten to the point of being undrivable in 27,000km. Isuzu use hard chrome liners with a chromed top ring and cast-iron others. Made by Mahle-Izumi.

My opinion is to keep ring materials and bore materials different to prevent adhesive wear. Ring tension affects friction, wear and fuel economy but hasn't got that big an effect on sealing.

I went with NPR rings from partsouq.com. Based on your information I'm going to file fit the rings to the max acceptable ring gap per 3B manual to help allow for extra heat swelling due to turbocharging.

 

[Darkwing58]

No clue on the oil squirter other than the hole in the end looks clear.

Keep in mind 700-750C from a pre turbo temp probe in my 1/8 wall welded exhaust manifold is likely much lower than the temps inside the combustion chamber.

There was a previous brutal overheat that lead to head replacement....Coolant blew out of a JB weld freeze plug(previous owner/mechanic) and water was no longer in contact with temp guage probe so the guage didn't go hot. She started slowing down on the highway Pushed in the clutch to pull over and it locked up with that lousy brown smoke out of the exhaust..............Replaced the head, 2 pistons were scarred, but not punctured and the bores were still go so I left them in but smoothed the sharp edges and high spots on the domes. Those were weak at that point.

I believe it suffered overheat prior to my owning the vehicle. Evidence of head replacement present. The head on the vehicle when I bought it had mismatched valves that were too large for the valve seats. Valves literally seated on the shoulder of the valve Flat on angle edge, due to nothing more than spring pressure. No way toyota put it out of the factory like that. It ran that way evidently, but the guy at the head shop said he had never seen anything like that in 20 years of doing head work.

.....................Oil level has not gone below the "cross hatch" on the dipstick. Meaning never less than 2 quarts from full since I've had it. Engine temp guage went as high as 3/4 of the way from L to H. Normally it runs at about 3-4/10 of the way L to H.

Time is important to me right now. I'm leaning toward trying to hone out the scuffs on the cylinders a new set of pistons , rings, rod bearings and reassembling. Even if the bores are imperfect I think it will hold up and run for some time. As jacked as it was I had over 400PSI compression on every cylinder except the one with the stuck ring. Reducing fuel and avoiding the interstate while enjoying some local 4wheeling, beach camping, etc... add towing and rental car to my insurance policy. If the engine lets go again That will be it for the 3B and me.

I'd kind of like to do a old school DIY cylinder liner replacement just for the learning experience, but when I crawled underneath to look at the bottom of the engine today the liners do not protrude. The block casting covers the bottom of the liners. I don't know how you get anything under the liner bottom to push or pull it out. Toyota has a Special Service tool for this, but looking at the bottom of the engine I have no Idea how you'd use it.....If I could see the liner walls protruding down and a way to insert the tool between the block and liner I'd understand, but I'm not seeing anything like that.

When I think about lost time I see 3B rebuild as 1 month+, in frame rebuild 10 days, "easy engine swap(something fits in easily and readily bolts up with available adapter)"4-6 weeks, "developmental engine swap(something big requiring clearancing and modfication of driveline/custom adapter plates)" 2+months.

You weld a bead down the cylinder, that will cause it to shrink a little and then push it out.

 

[Dougal]

You weld a bead down the cylinder, that will cause it to shrink a little and then push it out.

You weld a bead down the cylinder, that will cause it to shrink a little and then push it out.

I know a guy who accidentally struck an arc on the block deck while trying that. Ruined the block.

I prefer to pull them out with a plate and threaded rod.

 

[robmobile73]

I know a guy who accidentally struck an arc on the block deck while trying that. Ruined the block.

I prefer to pull them out with a plate and threaded rod.

Thanks for the information and reply to my thread. I finished the in frame rebuild last year. Holding up fine so far.