1HDT Rebuild Piston options (2 Viewers)

[jules781]

G'day everyone long time reader first time poster. I have sourced a 03/1992 1HDT engine for my 75 series I know im on the 80 series page reason being the motor is from a 80 series and 75 didnt come with em. Anyway I will get to the point, as alot are aware these early motors ran a different size bowl in the piston. Cause I am doing a full rebuild, I want to get the most out of it. Can I simply change the pistons to the bigger bowl size and using the correct injector washers to suit or is it a little more than that. Im pretty sure that the compression is the same as when they went a wider bowl they were also not as deep. Could someone shed some light on the matter and what would be some good pistons to put in it as down the track I will be doing a turbo upgrade and I will be boosting it but I want this thing right. Cheers.

 

[ozcrusier]

Give these guys a call regarding questions on your 1hdt engine or search there web site.
Engine Australia | Diesel Engine Parts, Cylinder Head, Diesel Engine Gaskets, Australia

 

[jules781]

yes I have spoken to them and not really giving me much help on what pistons to use. I want to know if I can use the later model pistons as they have wider combustion bowls. I asked engines australia and they say there not to sure. Only information I gathered was as long as I use the thicker injector seat washers then I can use the 42.5mm bowls.

 

[roscoFJ73]

Others have used the wider bowled pistons for rebuilds. Do you know why the information says to use thicker injector washers?

 

[jules781]

I think the reason being as the bowl is wider the washers that suit that piston are 1mm thicker to lift the injector up maybe to angle the spray pattern better for the wider bowl. But is it as simple as doing that, last thing I want to do is use these pistons and it dosnt work out and have to do all that work again. Anyone here built up a 1hdt

 

[zipdoa]

I think the reason being as the bowl is wider the washers that suit that piston are 1mm thicker to lift the injector up maybe to angle the spray pattern better for the wider bowl. But is it as simple as doing that, last thing I want to do is use these pistons and it dosnt work out and have to do all that work again. Anyone here built up a 1hdt

Did you ever find an answer to your question? Just about to start my 1HDT rebuild

 

[jules781]

Yeah did some homework I used the later pistons and washers. Only other differences were injection pump timing it is 1.19 - 1.24 mm for later engines.

 

[zipdoa]

Yeah did some homework I used the later pistons and washers. Only other differences were injection pump timing it is 1.19 - 1.24 mm for later engines.

Cool. Where did you source your parts? Did you get your injectors and IP rebuilt?

 

[Brad555]

Hi all, can you confirm which injector washers are for the later model ( larger bowl). Both came in the gasket kit. I'm on my second rebuild now, first from a turbo failure and this one due to a cracked piston. I've had the thicker washer installed and the injectors and chambers were pretty filthy.

 

[jules781]

Thicker injector washers for later model pistons. I be checking your injector spray pattern and injection timing because of the damage

 

[Brad555]

Thicker injector washers for later model pistons. I be checking your injector spray pattern and injection timing because of the damage

Thanks Jules, yeah I had the pump and injectors rebuilt for the first build and checked the timing and injector pattern on this occasion seemed good. Engine is running now but still feels like there is a slight miss/ unbalance when accelerating just above idle. I could be imagining it too!

 

[jules781]

Make sure you torque the injectors down over tightening them can cause the nozzles to balloon

 

[BJ70BOY]

Hi all, can you confirm which injector washers are for the later model ( larger bowl). Both came in the gasket kit. I'm on my second rebuild now, first from a turbo failure and this one due to a cracked piston. I've had the thicker washer installed and the injectors and chambers were pretty filthy.

View attachment 1310282

Brad555 I'm guessing you replaced your pistons on the first rebuild? Do you know what caused the cracking, and where did you get your pistons from?

 

[macca1590]

Thought i would dig this thread up rather than making a new one.

Im up for a rebuild on my early 1HDT as well, cracked a few pistons, and so far from what i can gather from my searches (someone correct me if im wrong but)

Using the later pistons and larger injector washer is best correct?
Also genuine pistons are best? are they the same as ART pistons? i did find some place selling ART pistons with the note "(genine toyota)" beside it.
And yes or no to ceramic coating? i have read some conflicting stories on weather its worth it or not.
Also anyone played around with the edge of the combustion bowls, i did read on some cummins stuff they like to remove the sharp edge of the combustion bowl to make a nice smooth radius into the bowl to avoid hot spots

 

[roscoFJ73]

Engines Australia engine kits have a good reputation and are generally well priced.

 

[macca1590]

I have talked to them on the phone and they sound like they know whats up. ill just have to make up my mind on how much id like to spend hahah. So no one has any feedback on ceramic coating pistons?

 

[mudgudgeon]

What are you hoping to achieve with ceramic coating?
1HD-T has piston crowns cooled by the oil squirters underneath, very different to a typical petrol engine

 

[gerg]

Ceramic coating might help mitigate hot spots and even out temps across the piston more decreasing thermal stress on the piston crown.

I wouldn't go radizing the rough edge on a piston bowl without considering carefully it's purpose. Lots of studies out there looking specifically at bowl shapes and injector angles and bowl tumble and how the edge of the bowl deflects the flame front away from the cylinder wall and prevents the flame front from easily crossing the top of the piston. Im not saying you can't improve it, but the odds are against you as it works in conjunction with the injector angle and the spray as it projects as a cone. Altering it without some serious thought would be like taking a die grinder to your ear canal to open it up so you can hear better. Subtle nuances on bowl shape have dramatic effect on combustion characteristics.

 

[macca1590]

What id like to achieve is a engine that will hold together at current power and torque levels (around 150kw and 600nm), it has been running on this set up for around 80,000kms now had a total of 563,000kms on the engine when it s*** the bed, injectors tested fine so im thinking it may be a combo of the tune on the warm side and pistons that have been up/down and hot cold a billion times and have just given up.
So really a standard rebuild will probably be fine for a long time but i figure while its apart i may as well do as much as i can to help avoid a similar failure in the future.

Im no expert but from what i can gather from my reading so far is that the ceramic coating helps keep some of the heat out of the piston, that along with the standard oil squirters keeps the piston temp down. So in a petrol engine the ceramic coating dose a similar thing?

Yes that makes alot of sense on the bowl mods, ill have to do some more googling and see whats out there, sounds like it may just be be safer to leave it be haha.

 

[dieselariel]

good morning im looking for a new kit of pistons on me 1hdt have only 18.000 kmts and crack a piston , at this time i am dismanteling all the the engine to see what is the problem im think the problem are in the injectors calibration but i dont now at this time , many vendors have very good price in pistons but the problem is the brand , the most are taiwam and corea and theare are not the best for me im looking for diesel poewer of australia the rewiews are very good i like toyota original part but the price is very expensive