LD28 Smashed Piston Crown

Discuss (and cuss) the Nissan LD-series OHC Six diesel engine, popularly available in the US in 1981-83 Datsun/Nissan Maxima Sedans & Wagons.

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hamahona
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LD28 Smashed Piston Crown

#1

Post by hamahona » 9 years ago

I have a 1981 Jaguar with a LD28 engine. When I obtained it, it was not running. The previous owner said that he replaced the injector belt as it was snapped. I put it together and got it started (first pop).

It was making a knocking noise and running rough. I released the pressure of each injector until I found out which one wasnt firing. Number two was not firing. I removed the head. Number 2 valves are bent open and hundreds of chips of metal were melted on the piston crown and ports of number 2. The knocking noise was the metal chips knocking on the head (sound like bearings). The cylinder bore is not scoured or scratched. In fact, there is not even a lip on the top.

I am still thinking whether I should get a second hand LD28 or overhaul this one.

1. Why would the valves clash with the piston when the engine is chain driven?

2. Is there a part that I will need to replace so the valves don't clash with the piston crown again?

3. Due to the fact, that there is no lip on top of the cylinder bore, does that mean I will get away without re-boring. Just fit new rings and obviously one new piston.

Thank you for your answers in advance.

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Last edited by hamahona 9 years ago, edited 4 times in total.

diesel-man
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#2

Post by diesel-man » 9 years ago

My guess would be that you are looking at the effects of too much starting fluid. If it did not have a turbo (none in USA from factory) the only sorce of too much heat to melt part of the piston would be starting fluid. Chips inside rolling around would bend valves. Need to examine the cylinder head. Perhaps a piston and rings would do it? Here a running engine is probably $500...so it is about the same either way...risk/reward.
Hope everything works out!!!

opie
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#3

Post by opie » 9 years ago

Gasoline wouldn't do it?
Two salvage yard engines being diagnosed for repair.

opie
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#4

Post by opie » 9 years ago

Gasoline wouldn't do it?
Two salvage yard engines being diagnosed for repair.

diesel-man
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#5

Post by diesel-man » 9 years ago

Unlikely that someone put gasoline in a diesel...but it happens.

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hamahona
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#6

Post by hamahona » 9 years ago

diesel-man wrote:My guess would be that you are looking at the effects of too much starting fluid. If it did not have a turbo (none in USA from factory) the only sorce of too much heat to melt part of the piston would be starting fluid. Chips inside rolling around would bend valves. Need to examine the cylinder head. Perhaps a piston and rings would do it? Here a running engine is probably $500...so it is about the same either way...risk/reward.
Hope everything works out!!!
Thanks for your reply. It does not have a turbo. There is quite a possibility that the previous owner may of used starting fluid, not sure. Wouldn't this cause more than one piston to detonate?

Possible the metal chips melted onto the piston and head are from the rings, I guess I will find out if I stripped the engine down.

There are quite a few front sump second hand LD28 complete engines here ranging between $200NZD and $800NZD. Thing is I dont want to be drilling the block to suit my rear sump setup. Probly end up over hauling the LD28 I have.

Thank you.

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hamahona
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#7

Post by hamahona » 9 years ago

diesel-man wrote:Unlikely that someone put gasoline in a diesel...but it happens.
The guy I bought the car off had bought it off the original owner. The original owner said the ip belt was snapped. Would it be possible for the engine to detonate if the belt was not fitted correctly?

diesel-man
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#8

Post by diesel-man » 9 years ago

hamahona wrote: The guy I bought the car off had bought it off the original owner. The original owner said the ip belt was snapped. Would it be possible for the engine to detonate if the belt was not fitted correctly?
Possible the metal chips melted onto the piston and head are from the rings, I guess I will find out if I stripped the engine down.
No chance that the injection pump belt caused it. Only starting fluid or a turbo will create enough heat to melt a piston..."you can take that to the bank."

The only thing that would/could make chips is some foreign object getting into the intake, but it still does not explain melted aluminum.

Anyhow, you might as well take it apart and see what it looks like...post pictures when and if you can.

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#9

Post by Carimbo » 9 years ago

Broken IP belt will stop engine immediately! No fuel to injectors!

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hamahona
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#10

Post by hamahona » 9 years ago

diesel-man wrote: No chance that the injection pump belt caused it. Only starting fluid or a turbo will create enough heat to melt a piston..."you can take that to the bank."

The only thing that would/could make chips is some foreign object getting into the intake, but it still does not explain melted aluminum.

Anyhow, you might as well take it apart and see what it looks like...post pictures when and if you can.
Yes, I think you have hit it right on the nail, starting fluid. I have enclosed some photos of the damage on my first message of this topic. Thanks

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hamahona
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#11

Post by hamahona » 9 years ago

Carimbo wrote:Broken IP belt will stop engine immediately! No fuel to injectors!
Thanks for that,it makes scenes to me now.

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exmod110
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#12

Post by exmod110 » 9 years ago

Loos like it dropped a valve seat form those pic's! why did it drop a valve? cant say, but it will cause the damage u have.
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windsock
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#13

Post by windsock » 9 years ago

exmod110 wrote:Loos like it dropped a valve seat form those pic's! why did it drop a valve? cant say, but it will cause the damage u have.
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Ahh, that'll polish out... :shock:

yes, looks like something was getting bounced around in there. What does the head look like? Any damage around the hole from the pre-combustion chamber? Can't quite see the whole thing in the valve photo.

Welcome to the forum by the way hamahona. Good to see another kiwi onboard.
Good roads lead to bad fishing.

diesel-man
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#14

Post by diesel-man » 9 years ago

exmod110 wrote:Loos like it dropped a valve seat form those pic's! why did it drop a valve? cant say, but it will cause the damage u have.
Looks like the valve seat caused it. I was more sure of starting fluid be the explanation...and before I saw the pictures.

Do yourself a favor and start with another engine. If the head looks that bad, the cylinder must have a little "rash" on it to. Sell the crank and rods to a gasser.

Usually if it overheats bad...bad...it can expand the head enough to let the seat drop down...get sideways...

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hamahona
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#15

Post by hamahona » 9 years ago

windsock wrote:
exmod110 wrote:Loos like it dropped a valve seat form those pic's! why did it drop a valve? cant say, but it will cause the damage u have.
Ahh, that'll polish out... :shock:

yes, looks like something was getting bounced around in there. What does the head look like? Any damage around the hole from the pre-combustion chamber? Can't quite see the whole thing in the valve photo.

Welcome to the forum by the way hamahona. Good to see another kiwi onboard.
Yes, I it looks like the valve seat broke off and bounced around and melted into the piston. I ended up buying another going engine Thanks you for the warm welcoming.

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