Help: 12ht engine missing and lost power. (1 Viewer)

[rideglobally]

1986 12ht engine, it was running fine then all of a sudden the engine seem to be missing and lost power. Opened the oil cap there is no big blow by pretty normal. Cracked open the fuel pipes coming out of the injector pump and to the injections, fuel is coming out. On two injectors there was no difference in the idle of the engine when the fuel pipe was cracked open. I am thinking something is wrong with the two injectors. What else can I do and check. Thx

 

[cuteo100]

This happened to me once then I realized that my fuel shut off lever wasn't fully opened.

 

[rideglobally]

This happened to me once then I realized that my fuel shut off lever wasn't fully opened.

There was fuel on the fuel line.

 

[cuteo100]

There was fuel on the fuel line.

In my case, there were fuel, but not enough fuel.

 

[rideglobally]

In my case, there were fuel, but not enough fuel.

I am getting back pressure at the intake, before I lost power there was something that sounded like a back fire is it possible that one or two of the valve is not closing properly?

 

[duncanrm]

Video?

The most likely cause is that you've sucked in some air in the fuel link.. have you reprimed?

 

[rideglobally]

Video?

The most likely cause is that you've sucked in some air in the fuel link.. have you reprimed?

Here the is the engine on idle on YouTube, if you listen carefully you can also hear the back pressure. you should know that when we cracked open the fuel line connected to the injector on two injectors there was no response and there was fuel coming out. On the other four the idle of the engine changed. Thx

 

[Radd Cruisers]

Does not sound good.

Two thoughts: cracked piston, or gasket blown between to adjacent cylinders.

Sometimes when a gasket goes between cylinders, there’s lots of exhaust smoke, high fuel consumption, considerable power loss, and of course no real change in blowby.

Cracked pistons make all kinds of different sounds, but often a hollow clonking sound, and usually lots of blowby.

John

 

[rideglobally]

Does not sound good.

Two thoughts: cracked piston, or gasket blown between to adjacent cylinders.

Sometimes when a gasket goes between cylinders, there’s lots of exhaust smoke, high fuel consumption, considerable power loss, and of course no real change in blowby.

Cracked pistons make all kinds of different sounds, but often a hollow clonking sound, and usually lots of blowby.

John

Thank you John,
1. There is a lot of smoke but blow by is normal.
2. There is a lot of black smoke, making me think it is the gasket.
3. What about the valve leaking?
How do you do a leak down test on a 12ht? Where do I attach the tool? As you know I have no glow plugs.
Should I just remove the cylinder and have a look inside if I cannot do a leak down test? Thx

 

[rideglobally]

Does not sound good.

Two thoughts: cracked piston, or gasket blown between to adjacent cylinders.

Sometimes when a gasket goes between cylinders, there’s lots of exhaust smoke, high fuel consumption, considerable power loss, and of course no real change in blowby.

Cracked pistons make all kinds of different sounds, but often a hollow clonking sound, and usually lots of blowby.

John

You are correct on the “gasket blown between two adjacent cylinder” see pictures. My question is what would cause this? Thx

 

[Radd Cruisers]

Cause can be simply age, or running too high boost (it would have to be quite high), or... the block and/or the head are no longer flat.

I experienced this on my own JDM 12HT, and it seemed to be due to erosion of the block and the head by inadequate coolant concentration leading to creeping corrosion under the gaskets.

Head shaved and re-done, and block was decked and bored.

As I mentioned elsewhere, if you trim any material from the block and/or head the bolt hole depths must be measured against the longest head bolt out of the 26 and checked for bottoming out by taking the stack height of the compressed head gasket and the head plus some allowance for stretch and compression under tension (a few mm).

~John

 

[Radd Cruisers]

Oh, and this usually happens with the inner cylinders - ie: less likely between 1 & 2, and 5 & 6, but more likely between 2 - 3 - 4 - 5...

You can also see the blue colouration of the combustion seal ring where it broke through - lots of heat there as the gases go back and forth.

Also looks like failure was imminent or actually happening at other places in the gasket.

~John

 

[rideglobally]

Oh, and this usually happens with the inner cylinders - ie: less likely between 1 & 2, and 5 & 6, but more likely between 2 - 3 - 4 - 5...

You can also see the blue colouration of the combustion seal ring where it broke through - lots of heat there as the gases go back and forth.

Also looks like failure was imminent or actually happening at other places in the gasket.

~John

Thank you for your help

 

[Radd Cruisers]

You’re welcome.

It sure sucks to have this happen, but it is a good learning experience.

I have 12HT parts like gaskets in stock if you need anything that you can’t get locally.

 

[roscoFJ73]

This engine was rebuilt if my memory serves me right

 

[rideglobally]

You’re welcome.

It sure sucks to have this happen, but it is a good learning experience.

I have 12HT parts like gaskets in stock if you need anything that you can’t get locally.

Sorry,wish I knew, should have ask. I am Slovenia, traveling

 

[rideglobally]

This engine was rebuilt if my memory serves me right

Yes I was

 

[rideglobally]

You’re welcome.

It sure sucks to have this happen, but it is a good learning experience.

I have 12HT parts like gaskets in stock if you need anything that you can’t get locally.

I send you a DM I will need the rebuild gasket set and the 26 cylinder head bolts. Can they be in Kamnik, Slovenia by Wednesday 7/27? Thank you very much.

 

[Radd Cruisers]

I have replied by email.
~John

 

[roscoFJ73]

Can they be in Kamnik, Slovenia by Wednesday 7/27?

Can you get the head checked for warping in Slovenia?