First post here. Mechanic, new to work on Hino engines. Working on a J08 with oil in coolant issue. No coolant in oil, even after running for extended periods. Issue still present with coolant bypassing turbo. Pressure builds in radiator as if head gasket is issue. Initially resealed oil cooler, then replaced with new unit after problem persisted. Manual transmission , so this is not an atf in coolant issue. Head pulled and checked for straightness, new injector cups installed. Head re-installed with new gasket. Oil in coolant now seems to be even worse. high pressure builds in radiator still, and large amounts of oil are put in to the coolant. Head, Hino tech at my shop is determined to pull oil cooler again. I am thinking it is an issue with an internal head problem or sealing issue of head gasket. Any info or common issues that may be known for this engine will be appreciated. Thanks, Nick
J08 oil in coolant issue.
- Thread starter NICKGRAU13
- Start date
Have the head pressure tested. Leave the cups in.
Who installed the cups? There's an o-ring behind them that gets replaced. The cup is installed with a special sealant then swaged into place. Were these things done correctly?
Oil cooler failure on these is rare. I replace them during rebuilds. I replaced one I dropped on the floor. I've never replaced one because of oil and coolant mixing.
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Who installed the cups? There's an o-ring behind them that gets replaced. The cup is installed with a special sealant then swaged into place. Were these things done correctly?
Oil cooler failure on these is rare. I replace them during rebuilds. I replaced one I dropped on the floor. I've never replaced one because of oil and coolant mixing.
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Also, resurfacing these heads is not recommended. There's no provision for adjusting idler gear clearance.
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Sent from my XT1585 using EO Forums mobile app
Like greasytshirt said I personally have never seen an oil cooler fail internally. Many leak externally but never a internal. Multiple headgasket failures though. Possible air compressor, but then again I have never seen one fail. How was the sealing surface of the block. They have had failures with porisity in the coolant sealing areas. They updated the head gasket sealing area because of this. Its on a tech tip if you have hinonet access. I would definetly suspect injector cups, proper sealant with the white hino sealant and suspect proper o-ring installation. I have my heads pressure checked for cracks. It sounds like you covered all these bases but those are the most common failures.
Thank you for all the info in both your replies. We are having the head checked tomorrow. The block itself has some pitting, but nothing worse than a few microns . block is straight, head is straight. The gasket used, was the new style with the larger o-ring openings. Not sure why we did not have it checked in the first place. I am basically the parts changer on this job, with not much input wen it comes to the way it is handled. It frustrated me when it was suggested to pull the oil cooler again. That is the point that had me seek out some input on here. The cups were installed by the main engine builder here, and I am not sure what material he used to seal them. I remember the manual suggesting 3-bond as the sealant, I know that was not used. I will have to ask him what was used. Again, thank you guys for the input. I will update when we get some progress.