3B Precups - The Final Day (1 Viewer)

[Capitalguy]

I've never worried about dropping pieces of my precups into my cylinders despite everything there being 33 years old and despite giving my BJ40 lots of heavy towing work throughout its life.

But then my coolant system has always been spotlessly clean, I've always run quality coolant, and I've always replaced or repaired my radiator (or any other coolant-system component) at the first signs of leakage. (And I have a policy of replacing coolant hoses and water pumps automatically after they've given me long-service rather than waiting for them to fail.)

The stock temperature gauge is fine as far as I'm concerned..

In my opinion, one of the key reasons a lot of people cook their engines REALLY badly is because they rely too much on their temperature gauges and fail to recognise their limitations. What I'm referring to of course is the scenario where the coolant no longer reaches the sensor/sender (because its level has dropped so far because of a leak and/or boiling) and the temperature gauge consequntly drops well back from the "overheating segment" on the dial to give a non-thinking driver the false impression that their overheating drama has miraculously disappeared.

I don't beleive this happened due to overheating, at least not while in my possesion, rad was always full of coolant, all hoses were replaced, including the two under the truck to the rear heater, block was flushed when I installed the turbo, I use a premium diesel coolant, rad is a 4 core in good shape with nothing plugging the fins.
Always had good heat in both heaters so that tells me circulation was good. Never towed with it, it's a hobby truck, I own and have been around equipment all my adult life, and you can tell when something isn't right, especially when you are the only driver. So I don't know. Whats done is done. For the 50 bucks or so I can keep an eye on things with the replacement engine.

 

[Toshi38]

Peter I agree about 50 bucks to keep an eye on things... I would put in the mechanical gauge... I was impressed at how much more it changed in day to day driving then the stock one. The stock one is good enough to tell when your truck is over heating and when its not. The mechanical one you can really tell when the temperatures are rising and falling. Combined with a good EGT gauge I'm sure it will help your engine last a lot longer. I definitely noticed I changed the way I drove after I added EGT and a good temperature gauge...

Let me know if you need any help getting that engine in there...

 

[Capitalguy]

Thanks for the offer,I will ask when the time comes but installation is still a bit away, head is in the shop, they did a vacum test and 2 intake valves didn't hold very well, not a big deal so they'll be doing touching up all the valves. Ordered valve stem oil seals today, parts from Radd came in today as well. Slowly poking away at this.

 

[Capitalguy]

Well it's been about 7 weeks, the head came back from the machine shop about two weeks ago. When I had it magnafluxed they found a crack between two valves.
So I sent it off to Montreal where they repaired it.

Had a guy from our club come in and adjust the valves, flywheel machined, new clutch and pressure plate.

 

[Capitalguy]

Slowly over the next few weeks I poked away at it evenings in that heat wave we were having and this past Friday I fired her up. All went well a few oil leaks where I forgot to tighten a turbo line. Runs like a top, installed a manual temp gauge, runs about 192F oil pressure is good.

 

[Toshi38]

Great work! was awesome to see it running on Saturday morning!

 

[gerg]

I agree the stock temp guage is crap, but I doubt overheating alone could crack precups. If you really overheated and dumped cold water in the engine maybe that could do something. I really think cracked pre cups come from hot shut downs that rapidly cool the cups from high temps. I heat up metal all the time till its red hot and it never cracks. Cool it rapidly and unevenly and your amlost guaranteed it will crack. I think people dont realize that half of the precup sits on the block and the other half is floating over the pre cup chamber. the block half will always cool rapidy while the suspended part will cool slower. Repeat this uneven cooling process and you will only get to do it for so many cycles. Lower shut off egt temps and you will have less disparity between the two halfs of the cup.

 

[Capitalguy]

Great work! was awesome to see it running on Saturday morning!

Stephen - Too bad I couldn't make it out with you guys, hopefully next month.

I agree the stock temp guage is ****, but I doubt overheating alone could crack precups. If you really overheated and dumped cold water in the engine maybe that could do something. I really think cracked pre cups come from hot shut downs that rapidly cool the cups from high temps. I heat up metal all the time till its red hot and it never cracks. Cool it rapidly and unevenly and your amlost guaranteed it will crack. I think people dont realize that half of the precup sits on the block and the other half is floating over the pre cup chamber. the block half will always cool rapidy while the suspended part will cool slower. Repeat this uneven cooling process and you will only get to do it for so many cycles. Lower shut off egt temps and you will have less disparity between the two halfs of the cup.

gerg - I've got a baseline to start with now, I know what I've done. I know now that the previous engine was apart at one time by one of the PO's, although I don't know what was done, or how it was driven.
On the plus side a bunch of other parts that would have needed replacing or rebuilding soon got done during this time out. Hopefully it lasts for another 26 years.

 

[Toshi38]

I'm going out next weekend... A guy I know bought a 4 door jeep so I said I'd go out and introduce him to 4x4ing... Or at least some light 4x4ing You're welcome to come out if you'd like to do a very stock friendly run I'm thinking of going to the same place we went last weekend with Brian

 

[Gengis]

I am glad the clutch pressure plate is well hidden inside the bell housing!! say no more.
must feel good almost being on the road again
G

 

[gerg]

It looks like youve done a great job. When I shut my truck off I watch my egts and idle it down to 350F ussally or 400F if I dont have time.

 

[Capitalguy]

I am glad the clutch pressure plate is well hidden inside the bell housing!! say no more.
must feel good almost being on the road again
G

Yes the color was a shock when I opened the box, works well on road, I haven't been off road with it yet.


It looks like youve done a great job. When I shut my truck off I watch my egts and idle it down to 350F ussally or 400F if I dont have time.

gerg - I try do about the same, although the odd time I do forget :whoops: