Foretravel Owners' Forum For owners and Fans of Foretravel Motorcoaches September 12, 2025 ...

Leaking 1996 dayco alt tensioner??

October 04, 2019, 02:57:42 pm

Looked through archives. Saw no tensioner leak issues. Noticed some liquid on bottom of alternator dayco original tensioner. Didn't notice it yesterday. Seemed like light oil??
When i replaced water pump 2 month ago I spun tensioner and seemed ok.
Any thoughts?

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Re: Leaking 1996 dayco alt tensioner??

Reply #1 – October 04, 2019, 03:03:53 pm

At 23 years old, I would just replace it.  I like the Gates tensioners.

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Re: Leaking 1996 dayco alt tensioner??

Reply #2 – October 04, 2019, 04:01:26 pm

Thanks Brett,
Well when there's a leak it helps to sometimes look up. Doh!!. Slight oat red coolant from 2 overhead thermostat clamps 3/8".
Carry on .

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Re: Leaking 1996 dayco alt tensioner??

Reply #3 – October 04, 2019, 04:18:01 pm

Probably a good idea to replace the tensioner as well.  Water/coolant don't do the bearing or tension/dampening mechanism any favors.

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Re: Leaking 1996 dayco alt tensioner??

Reply #4 – October 04, 2019, 04:29:02 pm

Don't see anything wrong with it. Looks cleaner than ours.

P

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Re: Leaking 1996 dayco alt tensioner??

Reply #5 – October 04, 2019, 04:35:33 pm

Good, short video on checking tensioners: http://www.youtube.com/watch?v=uTLV5IU_IMM

If OE, I am betting against it being good.

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Re: Leaking 1996 dayco alt tensioner??

Reply #6 – October 04, 2019, 05:28:02 pm

That's what our tensioner looked like before I aligned it. Video looks designed to sell Gates tensioners. No mention of pulley alignment that causes the same effect. Stretched belt will also result in belt/tensioner motion as the longer the belt is, the weaker the spring is.

Pierce

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Re: Leaking 1996 dayco alt tensioner??

Reply #7 – October 04, 2019, 05:52:53 pm

Pierce,

Totally agree that other factors will cause the same symptoms.

But verifying that the belt is not "jumping around" IS important.  That constant loading/unloading/loading.................. bearings is really hard on them.

Indeed, find the root cause and remedy it!

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Re: Leaking 1996 dayco alt tensioner??

Reply #8 – October 04, 2019, 08:04:32 pm

While we were getting ready to leave NC after buying our U300, the PO told us that they had been stuck in the middle of nowhere a couple of times when the hydraulic belt broke and they had to wait for road service. The engine got hot enough that the DDEC went into auto shutdown. Road service had installed a six groove belt as the eight groove kept jumping up on one side of the pump pulley.  I purchased a few spare belts before we headed across the U.S. We had only traveled one day when the belt broke again. The steering wheel in the coach effectively blocks my vision of the warning lights so I didn't notice the light until the coach suddenly lost power. A quick change in the rain got us going again.

After we got home, I looked up the correct belt. Unfortunately, Foretravel neglected to put much U300 belt information in the manual and never made any differentiation between the 1992 and the 1993 where they went from a single fan and vertical radiator to a dual fan and horizontal radiator. Our '93 had an eight groove pulley on the crank as well as on the pump. When I posted the problem, several members said that a six or 7 groove belt would work fine. Not being happy with that answer, I called Gates and talked to one of their engineers who said that if the pulley had eight grooves, the only correct belt was an eight groove belt. The new eight groove pulley was not any better than the old one until I started watching it closely and noticed it seemed to be moving back  and forth a small amount several times a second on the tensioner roller. This led me to start measuring the three angles and in a couple of minutes, I discovered that the whole tensioner was three degrees different compared to the crank pulley and pump pulley. The crank and pump pulley were in proper alignment with a straight edge so I pulled the tensioner but could not see any possible adjustment. So I experimented with washers of different thickness until the angle/degrees all matched. That was 50K ago.

Since then, I've seen other U300s where the angles match but the belt rides on one side of the tensioner roller. Fortunately, the large steel mount allow fore and aft movement where it bolts to the block so it's possible to have all the angles match and the belt to ride in the middle of the tensioner roller.

Because of the short time the factory took to build the mount and align the components, this is a fairly common problem as I have received several PMs with the same problem. This coupled with the steering wheel (in my case) blocking vision to the warning light. The DDEC II does it's best to shut the engine down but there is an override button. One owner was stuck as he started into a tunnel. Repeated use of the override button overheated the engine to the point the block was warped and the whole engine had to be replaced.

Attached photo shows the belt that fits our 1993 twin radiator fan U300. The earlier U300s with the single fan probably take a different belt as the pump only has to drive one fan. This is an expensive belt but buying it online saved us about 50%

Pierce

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Re: Leaking 1996 dayco alt tensioner??

Reply #9 – October 04, 2019, 08:08:31 pm

Attachment didn't work. Trying again.

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