Summer heat cleaning.

[dakazman]

  It’s been sweltering hot with humidity thru the roof.  After getting the AC in my van and a new evaporator/condenser in my el Camino my vacuum pump losses pressure. Found it low on oil so I moved on.
  My corvette after finding a loose center hubcap when I got my new tires installed,…found a missing bushing on the rear struts. A motorcycle that needs two diaphragms for the carbs and a fuel shut off. .. supply chain again. So what to do next? Cleaning up and organizing garage.
  It was a labor of love but on the side of extreme. I tore down my scaffolding that stored way to many parts for the lotus. So I decided to assemble the crossflow which were the majority of parts on the scaffold. All in all I can walk thru and work in the garage . I did a few small jobs on the lotus but now the list is narrowing down.  Good thing I’m retired.
  Dakazman
 

[BDA]

Good job! Congratulations for being able to motivate yourself in the heat and humidity!! Now it's time to 

[Richard48Y]

"Assemble the crossflow".
A project I hope to embark on soon.
Have any good tips for me?
Looking at 78mm pistons so need to find a machine shop to bore my cylinders.

[dakazman]

"Assemble the crossflow".
A project I hope to embark on soon.
Have any good tips for me?
Looking at 78mm pistons so need to find a machine shop to bore my cylinders.

    First of all I’m no expert on building engines, but when your ready you will get answers to all your questions and concerns.

    I found that the blocks have been neglected.
   Clean and retap all the bolt holes and make sure they can handle their required torque.
   Remove the oil plugs and clean passage. 
  I also recommend setting aside some time to read and re-read the details.
  Take it slow, I’m been so sore from torquing and have some ice packs ready for your shoulders and wrist. 

  Like they say , A Good foundation is peace of mind. 😉

   I think I have a separate thread on this engine, with installation of threadserts on some of the head bolts. I’ll see what makes sense either to post on it or start a new one.


  Yart racing , Mecky is assembling his engine also and uses 78mm pistons  . mine has 79mm in this 843.
Renault16shop has a few choices.

  Dakazman

[4129R]

   Clean and retap all the bolt holes and make sure they can handle their required torque.
   Dakazman

I thought we had established that some of the threads are J threads and re-tapping them causes problems.

[dakazman]

  4129 R ,
  That’s a new one on me .
 
  Now I have more research to do. How would you clean out debris from the bores deep down blocking the bolt from seating at proper torque?
  Thanks in advance
Dakazman
 
 

[Kendo]

I thought the J threads were on the rods. And apparently there are J thread chasers for that sort of cleanup.

[4129R]

They may be on the 5 main bearing caps as well, as both the big ends and the main bearings are torqued up without any spring washers or locking mechanism, they may have J threads to keep them from vibrating loose, and causing the bearings to wear out as we have heard recently.

[BDA]

I would not chase the threads for main and rod bearing caps or for head bolts/studs. I would clean them as best I can and then make double dog sure there is no absolutely liquid remaining in the holes.

[TurboFource]

I use a bolt and cut a slot in it with a "dremel" cut off wheel, the slot catches junk but
doesn't remove any metal....go a little ways in, back out, clean junk out of slot with a wire
brush and repeat....until you are to bottom of hole.

[dakazman]

  After a day of searching numerous manuals , I could not find any reference to J Threads .
I am a novice at building these engines however I do read pertinent manuals.

  4129r Where did you come across this information ?

   The parts manual shows the bolt as an M10 67  I included a picture of the tap used and can’t see any way for the threads to be damaged.

Dakazman

   

[BDA]

Recently, the topic of J threads started from a poster (sorry I couldn't remember his name and the forum won't let you search for terms with one letter words) who had a rod bearing problem. Going from memory, he theorized or knew somehow that the DPO had chased the threads for the rod cap bolt and that allowed the bolts to loosen or strip over time.

I had never heard of J threads either but I figured that J threads were the internal equivalent of rolled threads that are normal on bolts. This article explains in greater detail what they are (https://osbornproducts.com/whats_the_j_in_unj_screw_threads.htm). The larger root radius of the threads decreases the stress riser that would normally be formed by thread cutting tap. Chasing those thread would cut a smaller root radius and thus weaken the threads. It makes sense that J threads would be used in rods, for main caps, and for head bolts/studs because of the high and cyclic stresses.

[4129R]

  4129r Where did you come across this information ?

 

Dakazman

 

 The thread "Aluminum in oil in TCS" in the garage section of this forum.

[dakazman]

  Thanks guys,
  I find it interesting and had to Google them.  Man this engine building takes alot of time and patience. I'll get right on reading about J-Threads.
Just for fun I'll send of question to Montune, an engine builder in California. He is on Instagram and seems very friendly.

   I did read some of that thread but since I don't know anything about a tc, I stayed out of it. At work we would send off oil samples and through the lab they could identify every fragment of the particles and the location of that component of a jet engine.
  Then we had testing for foreign objects damage (FOD) using a FAST kit, that would identify what impacted the broken piece. I'm sure all weren't cheap and I heard upward of $500. usd.

   

[Richard48Y]

I doubt the J Thread issue is pertinent to Renault engines.
That came up on a Twink engine.