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Old 10-05-2022, 21:48   #1
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4JH3E-HTE Viscous Damper issue

Hola CF -


Here's tonight's greasy 4JH3E-HTE fun.

Found loose bolt on viscous damper sometime back and set it aside. Investigated this evening only to find it had been sheered (not just loose) which promoted further investigation resulting in finding another bolt had been sheered (both about 1/4" still stuck in the v-pulley). On the damper there are 6 bolts, the sheered ones are side by side so I am thinking this will lead to a cascading failure at some point.


Sooo.. thoughts.. considering the owner installed a mini-fridge sized Kohler genie in front of the engine leaving me a whopping 6" of space to conduct a magic extraction of the v-pulley - do I need to replace said v-pulley or is there a slim chance I can have the bolts drilled out? if so, I would think that since the bolts have been sheered (and other bolts looking like they are about to go as well.. ) the viscous damper is nfg & also needs replacement. If the v-pulley bolts are drilled out I would think the damper would need to have it's bolt holes adjusted to match up - something that doesn't seem like a super idea.


Any thoughts welcome on the subject..








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Old 11-05-2022, 01:27   #2
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Re: 4JH3E-HTE Viscous Damper issue

Regarding the viscous damper- I suppose that it may not need to be replaced (hard to tell) - the broken bolts should be removed definitely. I am curious to know what could have caused the failure of the bolts (age, loose 12V alternator, etc.)

Other symptoms the engine has going on is blow-by & white/grey (hard for me to tell) exhaust. I just replaced the injectors as there was a lot of goo (carbon) on them from bad fuel being run thru. Also, the engine was drinking oil (I attributed that to bad atomization of the fuel and the subsequent de-greasing the engine as it ran). I'm wondering if the balance and vibration on the crank shaft could cause any of the above..


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Old 11-05-2022, 20:29   #3
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Re: 4JH3E-HTE Viscous Damper issue

Spoke with my guru mechanic and also owner. Mechanic told me front end of engine has limited horsepower and possibly the 2 alternators (24 & 12) cold be the issue. Owner told me they had rebuilt the 24V alt bracket (twice). Looks like I'll be drilling out the two sheared bolts without having to remove the v-belt pulley. We'll see how that goes with a mirror and angle drill. Will post pics as able
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Old 16-05-2022, 06:13   #4
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Re: 4JH3E-HTE Viscous Damper issue

People underestimate the amount of harmonic vibration that alternators produce. By definition these units produce a pulsing electrical output and pulsing high frequency vibrations. With larger higher kilowatt alternators producing more vibrations than a smaller output alternator. Couple this with overly tightened vee-belts and you have the mounting hardware and drive pulleys becoming the focal point of this vibration and thus, the weak link in the entire system. Any loose connection points or under rated fasteners or connecting links will eventually break from the effects of this harmonic vibration. A well engineered system will have looser belt tension and possibly a Sprague clutch driven pulley.
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Old 16-05-2022, 06:20   #5
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Re: 4JH3E-HTE Viscous Damper issue

Hola FPNC - thanks for your thoughts. Sprague clutch will be my word for the day! What a cool concept. Anyhoo - still waiting parts & appropriate drill to try and remove the sheared bolts from the V-belt pull3y. Unfortunately, the engine never gets looked at unless I am onboard- believe this was a preexisting issue exacerbated by the ongoing swapping of alternators and inexperienced installation by owner and crew
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Old 22-05-2022, 14:45   #6
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Re: 4JH3E-HTE Viscous Damper issue

Update: Bought the following off of Amazon:
Naiyong Tools 5 Lathe Mill CENTER DRILL COUNTERSINK Bit Tooling SET , M35 HSS 5 % Cobalit Contained , Titanium Plated (1-5 mm)
and a set of left-handed drill bits. I carefully cleaned up the sheared bolts with a dremel bit on a angle drill, used a mirror & was able to get the bolt out. New damper in place with bolts -- Yippee--
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