uniberp Posted July 23, 2017 Share Posted July 23, 2017 (edited) I have. No mechanical failure (failed idler or waterpump or tensioner) to explain it. The only possible factor was hot city driving on a 90 degree day. Gates belt and NTN idlers. Edited July 23, 2017 by uniberp Link to comment Share on other sites More sharing options...
Subaru Scott Posted July 24, 2017 Share Posted July 24, 2017 Wish I had a dollar for every time I've heard "I think it jumped time." In all my years, I don't believe I've ever seen an engine that did so and kept running. Even the old american V8s that tried to use nylon coated aluminum cam sprockets (that trick never works), and ended up looking like circular saw blades... That's like saying, "I saw a ghost." There's always a logical explanation. Is it your car? Did you just buy it? Did someone else just work on it? What year? I suppose it might be possible with some of the cheap aftermarket tensioners. Link to comment Share on other sites More sharing options...
uniberp Posted July 24, 2017 Author Share Posted July 24, 2017 It definitely was a few teeth off, the plastic (right side) pulley. No doubt about that. This is a 5 year old engine with maybe 60k miles on it. All new idlers, water pump, oil-pump, tensioner. A few weeks ago the trans cooler line came off and sprayed the engine with ATF. I suppose some ATF could have seeped into the well-closed-and-completely-gasketed timing cover and helped the belt slip. Fortunately the owner was smart enough to shut it off immediately when hearing a bad noise, when first starting it the next morning after a hard hot day of city driving. I'm going to do a leak-down to test for bent valves, but after resetting the belt it started and ran ok, without any mechanical noise. SInce I'm in there I'll do the belt/idlers kit from mizunauto. Link to comment Share on other sites More sharing options...
idosubaru Posted July 24, 2017 Share Posted July 24, 2017 Is it a manual transmission? Is the belt guide installed above the crank sprocket (that's a part that's only on manual transmissions)? A few weeks ago the trans cooler line came off and sprayed the engine with ATF. I suppose some ATF could have seeped into the well-closed-and-completely-gasketed timing cover and helped the belt slip. Doesn't seem like it actually got wet but I've seen belts saturated with oil break in very short time - like a month or three. Link to comment Share on other sites More sharing options...
Subaru Scott Posted July 24, 2017 Share Posted July 24, 2017 I don't see how that could happen, especially after only 60k. Even if the tensioner completely failed, the drivers side cam, first in line after the tensioner, would surely skip first. If it is a manual and doesn't have the belt guide, then the crank sprocket would have skipped backwards and both cams would still be even. Link to comment Share on other sites More sharing options...
uniberp Posted July 24, 2017 Author Share Posted July 24, 2017 (edited) Auto transmission. Yes, it happened. The only explanation I can think is heat+oil vapor caused the rubber part of the belt to soften and slip. It was hotter than 90F here at the time. It must have happened when it was being turned off the previous day, or when started up the next, in their driveway. It was not making any clatter when running the last time it was driven. Edited July 24, 2017 by uniberp Link to comment Share on other sites More sharing options...
Subaru Scott Posted July 24, 2017 Share Posted July 24, 2017 What year, first or 2nd gen tensioner? I would pull the r. valve cover off and check for carnage in there... Link to comment Share on other sites More sharing options...
Fairtax4me Posted July 24, 2017 Share Posted July 24, 2017 (edited) Gates belt? Does it say where it was made? If there was no evidence of ATF inside the cover then oil contamination isn't likely. Oil vapor? Grasping at straws there. Belt isn't good quality, or the tensioner is failing are the most logical reasons. Owner said it made a noise when starting? What was the noise? Edited July 24, 2017 by Fairtax4me Link to comment Share on other sites More sharing options...
Numbchux Posted July 24, 2017 Share Posted July 24, 2017 I have seen it. '00 Impreza 2.5RS, 5MT. Components looked all in good shape (installed by PO, so unknown brand), belt guide present, and adjusted correctly. One cam (LH, IIRC, it's been awhile) off by 2 teeth. It sort of tried to run, but not really. New timing belt kit installed, timing reset, and that car ran great for several years. Link to comment Share on other sites More sharing options...
heartless Posted July 24, 2017 Share Posted July 24, 2017 had it happen on my 1990 legacy - noninterference EJ22 - no covers and it got stuffed full of hard-pack snow trying to get home (our road is one of the last to get plowed) 'Lucky' for me I was only a few feet from the driveway, and the "plow" (road grader actually) arrived minutes later... he cleared the road in front of me & the end of our drive, then helped pull the car to the driveway so the other half could tow it in the rest of the way fixing jumped timing SUCKS in the dead of winter outdoors. Link to comment Share on other sites More sharing options...
uniberp Posted July 24, 2017 Author Share Posted July 24, 2017 Gates belt? Does it say where it was made? If there was no evidence of ATF inside the cover then oil contamination isn't likely. Oil vapor? Grasping at straws there. Belt isn't good quality, or the tensioner is failing are the most logical reasons. Owner said it made a noise when starting? What was the noise? Gates belt made in USA. Still had visible timing marks on it. New style tensioner. 1999 EJ25D. The owner thought it was a rod bearing, (probably because that happened to the car before). I probably should not have started it, but even with the timing off, the engine turned over by hand, so I reset the belt and risked it. Seemed fine for the 10 seconds or so, revved it a bit and put it in gear. I'm gonna do a leakdown test next. There are pools of ATF in crevices on top of the engine, so it got a good soaking. Link to comment Share on other sites More sharing options...
Subaru Scott Posted July 24, 2017 Share Posted July 24, 2017 "Rod knocking," that's the sound of a collapsed newer style tensioner. My bet is when you turned it over by hand, is when it skipped. I have seen that can occur, because going that slow, the l. cam has the opportunity to snap forward on the back side of a lobe and throw all the slack at the r. cam. Link to comment Share on other sites More sharing options...
uniberp Posted July 24, 2017 Author Share Posted July 24, 2017 (edited) "Rod knocking," that's the sound of a collapsed newer style tensioner. My bet is when you turned it over by hand, is when it skipped. I have seen that can occur, because going that slow, the l. cam has the opportunity to snap forward on the back side of a lobe and throw all the slack at the r. cam. No. All the covers were removed before the engine was rotated at all. It was already skipped. It skipped during running, stopping or starting. Diagnosis by second hand reports of what it sounded like... probably not very accurate. I didn't even ask for a description. After seeing the oil and antifreeze were clear and full, I suspected the tensioner, so that's why I removed all the covers before doing anything. How do I diagnose a bad tensioner other than by watching for it to jump around? I put a "maintenance removed" tensioner on it just to see if it would run. It does run ok it seems. Edited July 24, 2017 by uniberp Link to comment Share on other sites More sharing options...
Subaru Scott Posted July 24, 2017 Share Posted July 24, 2017 No. All the covers were removed before the engine was rotated at all. It was already skipped. It skipped during running, stopping or starting. Diagnosis by second hand reports of what it sounded like... probably not very accurate. I didn't even ask for a description. I suspected the tensioner, so that's why I removed all the covers before doing anything. How do I diagnose a bad tensioner other than by watching for it to jump around? I put a "maintenance removed" tensioner on it just to see if it would run. It does. So, the crank and l. cam were lined up on the marks when you took the covers off? Link to comment Share on other sites More sharing options...
Fairtax4me Posted July 24, 2017 Share Posted July 24, 2017 Knocking sound and it skipped timing, tensioner is bad. If the tensioner was installed then removed and recompressed during the timing belt install there's a good possibility it was damaged. These have to be compressed VERY slowly or the valve mechanism inside WILL be damaged. Link to comment Share on other sites More sharing options...
uniberp Posted July 24, 2017 Author Share Posted July 24, 2017 So, the crank and l. cam were lined up on the marks when you took the covers off? Yes, crank and left cam were lined up. Right cam was about 5-6 notches off as I recall (I was shocked to see it). VERY apparent. Right cam sprocket is plastic, and with fingertip touch the teeth are not as sharply edged as the metal left-side-sprocket. No wear apparent, and the shaft turns smoothly. Knocking sound and it skipped timing, tensioner is bad. If the tensioner was installed then removed and recompressed during the timing belt install there's a good possibility it was damaged. These have to be compressed VERY slowly or the valve mechanism inside WILL be damaged. That's possible, but this engine has not had the covers off since it was new, about 60k miles. Rebuilt by a very reputable Subie engine builder specialist. I will still recommend him. Contact me offline. Link to comment Share on other sites More sharing options...
Fairtax4me Posted July 25, 2017 Share Posted July 25, 2017 Then it's bad because of age. Happens even with OE stuff sometimes. Sounded before like it had been replaced recently. If it's 60k old it shouldn't fail, but it sounds to me like it has. No telling exactly why, the new style tensioners just don't hold up like the old ones do. Link to comment Share on other sites More sharing options...
uniberp Posted July 29, 2017 Author Share Posted July 29, 2017 (edited) Then it's bad because of age. Happens even with OE stuff sometimes. Sounded before like it had been replaced recently. If it's 60k old it shouldn't fail, but it sounds to me like it has. No telling exactly why, the new style tensioners just don't hold up like the old ones do. That must be it. I tested the compression (with reset timing) in all 4 with a crappy HF quick connect compression tester and all are the same, even though the dumb gauge reads about 40% low (calibrated against a more precision bicycle pump). I'm just going to pretend it is due and put in a timing kit and water pump. Leakdown test showed nothing either. I'll check it again after a thousand miles or so, in case one of the valves might be slightly bent and start to burn. Edited July 29, 2017 by uniberp Link to comment Share on other sites More sharing options...
AdventureSubaru Posted July 29, 2017 Share Posted July 29, 2017 I had one slip on a failing tensioner. Was only off by a tooth or so, but it sounded pretty normal. Completely gutless going up a hill. Limped it a couple miles home and was pleased to find it was just slipped timing. (non interference. a 96 ej22) Link to comment Share on other sites More sharing options...
WoodsWagon Posted August 3, 2017 Share Posted August 3, 2017 Towed home a 99 forester which still ran but had jumped two teeth on the drivers side cam. The toothed idler pulley had blown out its bearing and was riding on the races. That was more slack than the tensioner could compensate for. Put a new idler on it, set the cam back in time, and it ran great for another couple years before the driveshaft blew a U joint and punched the auto trans shifter through the center console and the owner junked it for heroin money instead of fixing it. Jumped time on a non-interference EJ22 when plowing through a snow plow bank trying to get on to a trail. I was running without T-belt covers and packed enough snow in to slip the belt. I've got an 01 forester ej25 with bent valves on the passenger side. It hit a tree in the drivers side, the fan motor broke the timing belt cover right under the A/C compressor and a broken piece of plastic rode the timing belt over to the pass side and skipped it over that cam pulley. Link to comment Share on other sites More sharing options...
idosubaru Posted August 3, 2017 Share Posted August 3, 2017 as FT said OEM stuff can fail prematurely, timing belt failures have occurred on stock Subaru's with untouched timing gear before 100,000 miles. not sure of anyway to prove either one, but a tensioner needing recompressed even during an initial install is not shocking and probably higher odds: If the tensioner was installed then removed and recompressed during the timing belt install there's a good possibility it was damaged. These have to be compressed VERY slowly or the valve mechanism inside WILL be damaged. Link to comment Share on other sites More sharing options...
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