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L18 burning oil + comp. test + rebuild


Genaro

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Well this is the thing... the rings are forced against the cylinders by combustion pressures. Driving at 1/4 to 1/2 throttle will not be enough to break them in properly and by 500 -1,000 miles they have worn down and lost the ability to make any tighter seal. The crucial time for good tight ring seal is in the first 20 miles before blow by gets a head start.

 

 

If you tend to 'drive it like you stole it' then drive it 'like you stole it' right off. (well, keep below 4K for 100 miles or so, DON'T lug it and keep the RPMs changing) If you drive it normally, drive it 'like you stole it' for the first 100 miles then drive slower. Your engine will seal better, have higher compression and burn less oil for longer.

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Well, i went for a 30 kms/20 miles test and it performed pretty well... Always following your suggestions about rpm's and speed changes... Temperature was a little below half like always before, and measured with the heat gun at the thermostat housing is 75-80 celsius.

Acceleration is worse than before, a small amount of dark smoke comes out the exhaust every now and then...i think that i will change the muffler, it might be clogged with carbon deposits from the many liters of oil that went thru it.

Carburator is really out of tune, tomorrow i will follow Mike's instructions to try improve the performance.

When i parked it i found that there is a small coolant leak on the radiator or around, it is so small that i could not find the source with the engine running...maybe i broke/puncture a tube while removing the engine...yeah, i know...i should have the radiator removed prior to do so... Coolant level was a tad lower after an hour being parked.

 

Oil level is stable and pressure is 38-40 at idle, depending on the carburator mood...

 

Thanks to you all guys ! 

Im very happy with my truck being back on the road... I've saved 60% of the repair cost, i've learnt a lot and i'm sure of why and how everything was done. 

 

 

Edited by Genaro
Mispell
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Ok... I've found the leak on the radiator...there was a pinhole on the bottom "tank", i was able to remove some fins, scratch the paint, clean and apply some epoxy compound to the orifice.

After some time i put everything back on the truck and ran it for 10 minutes.

Looks like the thermostat took some extra time to start opening or an air pocket prevented the coolant to flow, because the temperature went a little over half scale for 3-4 minutes and then suddenly dropped to a little less than half. 

 

Im searching online for a replacement but looks line i will have to adapt one....no luck finding an "original" one yet. 

 

Anyway, i will try not to use the truck until i solve this, i dont trust that fix at all...it wouldnt be nice if it decides to leak at the very moment that im not looking at the temp gage and i overheat the just rebuilt engine...no no no... and also, if that hole developed, there must be more on the way. 

 

I didnt dare to put one of those "leak repair" magic liquids/powders...

 

Thanks for the advices and support! 

Cheers...! 

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  • 1 month later...

Ok, 250 kms since rebuild... It runs pretty well...

Since rebuild, the oil pressure started to go lower and lower at idling as kms went by, down to 15-18 psi, i guess the oil pump was also tired...so i've installed a new one (taiwan sadly) and pressure is now 28-32 at idling and running temp. 

I've changed the oil at 200 kms and replaced the pump... 

Radiator didn't leaked again, but anyways i was lucky and i found an brand new original radiator for u$s150...still waiting for it to arrive. 

 

IMG-20190516-161343529-BURST000-COVER-TO

 

Cheers from the south of the south...!

 

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The D21 Nissan truck known here as the Hardbody uses a high volume pump for the oil. Maybe this is what they gave you? I had an old L20B that idled at 17 and a used D21 pump raised it to 29 at hot idle.

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I dont know about the oil pump, Mike... I compared the internals from the two pumps and they looked exactly the same...

 

I forgot to mention that i also replaced the muffler on the exhaust... Its a 10cm/4" longer that the one that was installed, so the sound changed completely... It lost it's charm, but my neighbourgs must be happy, and thats good for me. 

 

IMG-20190517-174126110-2.jpg

 

Thanks ! 

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On 5/16/2019 at 5:25 PM, datzenmike said:

The D21 Nissan truck known here as the Hardbody uses a high volume pump for the oil. Maybe this is what they gave you? I had an old L20B that idled at 17 and a used D21 pump raised it to 29 at hot idle.

Do you still have that comparison pic?

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The '89-'90 240sx KA24E had them but all the later KA24DE did not

All KA24E and KA24DE truck engines have them.

 

I just pull them from Hardbody trucks. You cannot tell from the outside when on the engine, you have to remove them and look inside that inlet port in the picture. If buying one KNOW what you are looking for when it arrives.

 

Oil 'bleeds' past the main and rod bearings, the oil squirters  on the timing chain and the valve train. This does not change much with RPMs so if you are pumping more oil the pressure will idle higher and rise sooner at lower RPMs. This is good if running a spray bar.

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  • 1 month later...

Well, truck was running fine...

I changed the manifolds gasket due to a leak taht it developed between exhaust ports 2&3 and the manifold....cause i couldn't torque those two almost impossible to access bolts. 

This time i managed to tighten them more than the previous time. 

 

But when i tried to start the engine i wouldn't run....i checked for spark and it was giving me one everytime i stopped cranking. 

I installed the old distributor and it ran good...i guess something bad happened to the electronic one. 

 

Sadly , it runs like in the video...i cannot figure out what is happening here... I havent touched the timing, advance, valve lash....nothing, just replaced the gasket...

 

 

Thanks for any opinions ! 

 

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Were any of the plug wires off?

Did the coil wire come off during tightening?

 

Make sure distributor is tight and well grounded.

 

The START and the ON signal wires from the ignition switch should both go to the coil + and the EI module.

 

The second distributor is points???

 

Are you using a ballast resistor with the EI distributor?

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20 minutes ago, datzenmike said:

 

Were any of the plug wires off?

No, only during spark test...

Did the coil wire come off during tightening?

Yes, i've disconnected it for the gasket replacement for easy wrenching.

 

Make sure distributor is tight and well grounded.

Done...

 

The START and the ON signal wires from the ignition switch should both go to the coil + and the EI module.

I've reinstalled and connected the original points distributor as it was before.

The second distributor is points???

 

Are you using a ballast resistor with the EI distributor? 

I've followed the instructions that asked for bypass of the resistor when i installled the EI dist... Now everything is back as it was, but i will re-check, i may have connected something wrong... 

 

Thank you very much!!! 

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Well, i wasn't able to do anything on the truck the last 3 days...

I've started from scratch and figured out that in the previous troubleshooting i've made after changing the manifolds gasket i tought i've connected something wrong and replaced the E-distributor with the original points one for no apparent reason. 

Obviously the main reason was this

 

IMG-20190728-234121898.jpg

 

Seems like i dropped it to the floor and didn't checked after, it was at night in the driveway and with 2-3° celsius temperature. Lesson learned...i won't work again in those conditions...! 

 

Now the engine runs properly....thanks for the help! 

 

 

 

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  • 1 year later...

Well...i've found two of these beauties in an online store. 

 

IMG-20200901-135600323.jpg

 

Truck's been running just fine since i've "rebuilt" the engine, gas mileage is good, no oil consumption and some minor carburation issues every now and then. 

 

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