Author Topic: rear coolant log  (Read 270 times)

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Offline Bob_C_CT

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rear coolant log
« on: October 23, 2017, 07:16:10 pm »
I found my rear coolant log developed a slow leak. So the next day I was prepared to remove and replace the two orings. I took the advice of the pros and removed the carbs, thanks Steve aka SISF, I used the heat gun and pulled the carb rack right out.
Anyways I found that I must of rolled and/or just pinched the left oring when I did the water pump, thermostat and all new hoses and seals 3 years ago.

4 hours total labor, starting from pulling the Tupperware to getting it all back together., including two operating temp coolant flushes.

One thing I did find taking the log out was I had to use a wooden wedge against the engine to get the log out and putting the log back into the engine I couldn't get it in by hand. I had to use the screws to get it to go back in while I checked that the orings stayed in place. Is this normal or is it supposed to be put into place by hand and the screws are just hold downs. I believe the later as the screws are on the upper area of the log and the orings seem further info the engine on the top and slightly less on the bottom. All is well now with no leakage after a couple hour ride after I was done.
« Last Edit: October 24, 2017, 01:16:53 am by Bob_C_CT »
97 C10,ZRX Front, Meanie Rear

Offline GKreamer

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Re: rear coolant log
« Reply #1 on: October 24, 2017, 11:27:32 am »
When I replaced my coolant log o-rings (front and rear) about 18 months ago MOB suggested two things that worked for me: 15W fork oil on the o-rings and a popsicle stick to push the o-rings to make sure they seated properly.  I was able to install by hand and not use the bolts.  I also used scotch brite in the logs and repainted, except where the o-rings sit.

Offline connieklr

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Re: rear coolant log
« Reply #2 on: October 24, 2017, 04:02:43 pm »
I've done this on a couple of bikes, and also had to use a little mechanical persuasion to get the manifolds loose, and moving. Once out, cleaned the "spigots" with a wire brush to get rid of the scale and corrosion. Today, I would use my bead blaster but didn't have one at my disposal back then. A smaller wire brush was used to get up into the pockets to free and rid them of scale and corrosion.

For insertion, the pockets and spigots were treated with Cat anti-seize I had left over from my Caterpillar mechanican days. They slipped into place with no hesitation and I didn't have to fook with the o-rings to keep them in place.

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Offline Bob_C_CT

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Re: rear coolant log
« Reply #3 on: October 24, 2017, 04:45:04 pm »
Thanks GKreamer and connieklr for the responses.
I used scotch-brite in the engine ports and on the log around the oring groove areas, then lubed the engine ports and orings with a thin coat of vegetable oil.

It didn't seem right that I couldn't get it assembled by applying hand pressure on the log itself. The force used on the wooden wedge between the engine and log to disassemble seemed to equal the force to get it back together.

I did make sure the orings kept "going in" straight with a blunt ended tweezers and inspection mirror while I assembled it.

But as stated the top of the log outlet tubes looks like they are further in the engine by 1/64-1/32 of an inch as witnessed by the relationship of the orings to the engine ports up while tightening the mounting bolts evenly with minimal amount of torque applied. Not much bolt pressure needed to start the log into the block, but not able to push further by hand and proceeded to apply a little more torque on the bolts as the log was being seated deeper, but not enough to worry about stripping threads. After and during install I can't budge the log to try to align it better in the up and down position.

I must have a Monday morning or Friday afternoon rear coolant log that isn't quite the right size/orientation between the two outlet tubes. I may have to look into buying a spare so in case of a premature leaker I will replace the log.

I tried numerous times to install by hand with the front of the thermostat housing hose off so as to have the log/thermostat housing assembly in a free state.
In hindsight, I probably should of pulled the orings and dry fitted to see how much variation I had in the clearance between the log outlets and the engine ports.

97 C10,ZRX Front, Meanie Rear