2TG-3T Hybrid Discussion

[Celica_73]

For back gorund info please visit
http://www.toymods.net/forums/showthread.php?t=35481

As this is the third time in 4 months i've had to pull the engine apart i really want to get to the bottom of this.

Process this time rebuilt the engine using same pistion and rings as last time Which are Endurotec Pistion fly cut to suit and hasting rings. Engine currently has 110 miles since rebuilt 20 of which were clocked up on the dyno tuning. Engine has again drop compression in cylinder 1 to 55psi dry 75 psi wet where the other 3 are 175psi dry. Engine was running lean to start with and has been rejet to suit but the engine deveploed the blow by on the Dyno Car only had 60 miles on the clock before the tuning.

Dyno tuner found spark leads faulty and replace, spark plug wrong temperature, advance curve way too retard (but left alone).

Engine is still currently together as I want to find the problem and fix it this time before the rebuild! Has anyone heard bad things about these pistions and rings? Any ideas welcome.

My next step is to pull the carby off Cylinder one and check all passages and ports. Check and to check Fuel pessure.


Thanks
Jason

[TA23 Racer]

Hi Jason I think I posted a couple of times with you problems.
Sounds like you doing every thing right, the carby problem sound very logical.
I know you don't want to pull it apart yet so can you see signs by looking down the plug hole with a stork light. May be strip the carb very carefully over a white cloth a look for debris check main jet well and emulsion tube etc won't take much.
Oh and check all the jets are the same size as each other with jet drills don't trust the numbers lots of us drill them out so they might not be all what you think. I have been duded a couple of times this way.

Cheers Dave.

[allencr]

Is it always the same cylinder? Is it always next to or under a flycut?

Before the break/meltdown, did its plug look remarkably different from the others?
Checked the ign timing for ALL 4 cyls - the distrib. shaft may be bent or cam lobes not symmetrical.
Cam timing for that cylinder checked against the others?
Any special tricks/modifications to the cooling system that might overheat the head for that cyl.?
Any special tricks/mods to the air cleaner and/or intake system that might affect that cyl.

[GasedT18]

Hi Jason,

some basic questions.

1. Did you have the block re-bored or honed?
2. If not did you measure the bores for roundness (how oval are the bores) and size?
3. If not did you remove the unworn lip at the top of the bore?
4. Have you measured the ring grooves depths and heights and the ring dimensions and have confirmed they are a proper fit?
5. How hard are you pushing the engine - what is your RPM redline?

Cheers

David

[Celica_73]

TA23 Racer
The jets were the same as the 2TG orginaly but only got changed on the dyno by the operator. As for jet sizes been different I Trust Rodger as he was the supplier But will get them all the same. The idea of a block emulsion tube is possible as after rebuilting the carbies last year i get have a partly block pilot jet from the string of cloth i was useing to wipe the inside out with.

allencr
Yes it is the same Cylinder and yes under a flycut which is also the Thrust side of the pistion.
No special mods to cooling system all standard including the fan setup. Air cleaner is a Lynx Foam system common for there engines nothing special and same as what the 2TG had. Cam timing is the same across all cylinders checked on assembly. As for cam profile the cams were ground to same prior to first assembly.

GasedT18
The block was rebored at first hybrid assembly but only rehoned for second assembly So bore should be round both honed were done by the reconditioner. How hard have i been pushing the engine not hard at all after the first engine destorying itself i have been baby this one and only last 1/100th of the time. RPM limiter set as 5000 but never pushed it above 4. Ring were triple checked last time and were check first time both time fine with twice the end clearence stated in the toyota manual.

[Wil8115]

does the #1 plug show signs of running lean?

How hard are the hastings ring?

with only 120miles, it might not be seated yet.

Which break in style did you do ?



On the suggestion of my machinist,(fully built engine, not stock specs, not even close)
Broke the cam in.. 10mins varying rpm 1500-2000.
top off coolant.. then beat the hell out of mine, full pulls 1-2-3-4 , then engine breaking 4-3-2. did that 5 times. by the 5th time it was running very smoothly, crisp responce, etc.
that was almost 3 years and 29k miles ago..
make sure engine is Fully warmed. don't ever beat on an engine when cold.

[Celica_73]

Wil8115
Running wasn't attempt second time due to destorying the pistion first time after 6000 mile the aim was just to get to the Dyno. First time was told just to running slowly keep rpm llow and load the engine up (climb log hills) Which i did. No the cyclinder is dead not even after the first start did i get blow by. The current blow by is the same as last time it blow the piston which is 10 times worst the before the 2TG was rebuilt.

Cheers for the input but

[Wil8115]

long hills is fine for seating the rings under load.. but you would also need to engine brake down the same hills to seat the rings the other direction as well.

does the #1 plug look black, wet, brown, dry, white specks, cracked ceramic, burned electrode? anything ? Properly reading the plugs can tell alot about how a cyl is firing.

qiuck thoughts.
#1 top ring, or #1's 2nd ring installed upside down,
a low spot in the cyl wall.

unfortunetly sounds like it needs torn open again for proper inspection

[Celica_73]

Yeah what i did the first time was drive it up Dorrigo and back down 15km hill climb
I can say personally the rings were install correct as I install them myself and double check prior to install piston. Spark plug have only 40 miles on them and look nice and clean ceramic and clean and dry. Older plugs the tuner keeped so not sure of their condition I believe black due to incorrect temperature rating.

I realise the engine does need to be repaired and inspected but I'm just trying to locate the problem before the rebuilt as I'd prefer it to be my last for some time. Gaskets kit, rings, pistons, machining piston costing about $800 a time. At this stage thinking it would have been cheaper and easier to throw a Beams 3S in then the 2TG-3T hybrid

Cheer

[GasedT18]

Jason,

I'd be taking it back to your engine reconditioners and then after run-in to your tuner.

How much play is there between the gudgeon pin and the rod and the piston? When you fitted the pistons did you use a ring compression tool? How did the pistons feel when sliding it up and down in the bore (after oiling).

Provided that the mechanicals are sound, I would be looking at reasons for the engine running lean AND that your oil pump is coming up to pressure AND all of the oil galleys are clear AND that you are using appropriate oil.

If it runs properly on the dyno (I'd be asking your tuner to set it on the rich side of tune) I would be looking for reasons why the engine might be leaning out; fuel pressure/pump, lines, filter, fuel bowl is filling properly, jet flow etc - but the tuner would/should know this.
Did he do a road test?

Do you know what pinging sounds like?

A mechanic of mine states that a lot of 'modern' engines ping especially on crap (low octane) fuel. My 3T-C (on LPG, naturally aspirated) pings noticeably in hot weather climbing hills, a definite rattle sound, but I've never blown a piston. At some stage I'll fit a lamda controller and oscillating valve. Your tuner should be able to relatively safely show you what pinging sounds like - it was a mystery to me for a long time but when I switched to gas I couldn't miss it.

Then it is a matter of whether you are getting any starvation around corners. An O2 sensor would be a big plus as would a knock sensor hooked up to a data recorder.

You've used Hastings rings on all rebuilds. While the cause of your problems is likely to be leaning out it might be wise to use a different brand of ring.

The difficulty is when you try different things you can't be sure what change fixed the problem.

I can sense your frustration - been there, done that.

Here's a tip - when cleaning carbies use a lint free wipe ;-)

Good luck,

David

[Celica_73]

OK one little thing I forgot to mention is my dad is a motor mechanic was over seeing the rebuilt that I did. Yes a ring compression tool was used and pistons were firm to slide in as my father did this part and didn't say anything about being over tight so I'm assuming to be normal. Play on gudgeon pin personally didn't check. Block was dipped last time by the reconditioner.

I'd be taking it back to your engine reconditioners and then after run-in to your tuner.

Mate that is exactly what I did last time still didn't help engine blow up on the dyno and engine is running on the rich side for run in purpose. Just the engine isn't lasting longer enough to do anything with. He did do a road test but the engine was already stuffed by that time! Have purchased a knock sensor and a oxygen sensor for that very purpose.

Do you know what pinging sounds like?

Yes I know what pinging sounds like and the car didn't appear to be pinging. If it had I think the Dyno tuner would have picked it up.

If I'm not mistake but for an engine to destroy itself in less then 110 miles or 200km then there has to be something major!

Just pulled the front carby apart. Can't see a thing wrong all jets were clear (but should been replaced due to rejeting). All ports look to be clear. This thing is driving me nuts. Has anyone used a Colortune Plug before? Are they worth while purchasing.

[Celica_73]

Just done some reading about the Solex carby's I have a S4 (4 screws in top cover) 40PHH. Has no bleed pipe/emulsion tube, has no external float adjustment. What is called the Independent Type main jet system.

[styler]

i had a piston go down on the hybrid, turned out the venturi locating screw in the
dcoe weber had fallen out and the venturi rotated blocking off fuel as far as i know.
caused ringlands to break and generally sucked all round. i doubt this is your problem
but it has the same effect, ends up about 70psi dry, 130 wet i think on the cylinder affected.

[TA23 Racer]

Hi Jason, shit it sounds like a lean out problem on #1 again with another broken ring land. Sorry when I said take it to the dyno for jetting I meant to say don't drive it, run it in or anything else, just go straight to the dyno. Get the operator to run it in on the dyno with the O2 sensor on straight from the start. He will see if something is amiss straight away.
Where I work we always run in on the dyno we pay for 40-50 dyno time while we can monitor everything then if it's all looking happy we fire into the tuning mixture & timing.
Thinking that carb might need to go to a carby shop for a good dipping and clean, they can be bastards sometimes when they've had a touch of water in them.
A tear down of the engine will really help though to see if it's a broken ring land or a ring butt or 4 point scuff. Mind you this will tell you just how lean seeing all the other cylinders seem ok but it would be nice to check them too.

Jesus thats long sorry bloke but you are getting the full job, Cheers Dave.

(You've got 3 out of 4 so it's all experience) Really trying to get a good result here!

[TA23 Racer]

Shit Styler 45 Webbers are f-%&cking natorious for it but I hav'nt worked on a solex for a long time worth checking out. The booster for the main jet needs to line up with main jet port.
Good work Styler I've just realised how many horror stories I've blocked out.

Cheers Dave the slow typer.