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| 4G15 Timing Belt http://4g61t.org/forum/viewtopic.php?f=17&t=40081 |
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| Author: | Sunchaser [ Wed Mar 25, 2015 8:31 pm ] |
| Post subject: | 4G15 Timing Belt |
Well my timing bolt snapped the other day. I didn't hear anything metallic or horrendous when it let go but I have no compression (valves open/bent). I tried turning the cam but couldn't; should it be easy to turn? I'm gonna try and cheap out and want to know how to diagnose if the valves are still good without taking the head off. Also, would it be a bad idea to change everything (timing belt, water pump, cam and crank seal and not do the tensioner? The tensioner is almost as much as the water pump ( cheapest rockauto parts) and cheaper the better in the 4g15 engine department but I don't want to be retardedly cheap. How bad of an idea is it to get a $4 timing belt? Any timing motor hints or tips would be greatly appreciated, kinda walking into unfamiliar territory. |
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| Author: | UnderPSI [ Wed Mar 25, 2015 9:10 pm ] |
| Post subject: | Re: 4G15 Timing Belt |
The head is definitely going to need to be rebuilt. Hopefully the valves didn't make to much contact and the pistons aren't damaged. |
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| Author: | Sunchaser [ Thu Mar 26, 2015 3:09 am ] |
| Post subject: | Re: 4G15 Timing Belt |
Ok then ill just skip trying to save what little life this old head has and pop on a low mileage head. I don't know how much longer I am going to keep this engine hence the cheaping out on motor parts. Ill pull the head and see what there is to see. If I did it this weekend what would I cover the top of the block with, or could I just snug the old head back on? |
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| Author: | 89Mirageman [ Thu Mar 26, 2015 7:47 am ] |
| Post subject: | Re: 4G15 Timing Belt |
Pretty sure the 4G15 just uses a spring for a tensioner so no real need to replace that. Also I'd have no issues using an after market belt on the 4G15, they are made to OE specifications. |
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| Author: | Flying Eagle [ Thu Mar 26, 2015 9:01 am ] |
| Post subject: | Re: 4G15 Timing Belt |
Grab a sheet or rags and cover the top of the block. If you have some way of draining the block so coolant is much lower than the mating surface of the block to head, then you won't get coolant all down your head bolt holes (those must be blown clean!!) and down into the piston top area. If you had leak down tester you could check things for sealing after installing a new belt, but if the motor locked up in any way while turning, then you do have a problem. 8V 4g15's were non-interference, 12V were indeed interference if memory serves me well after all this time without one of those motors. Find a good head at a machine shop, or take it to one and get some valves, clean it up and re-install. Just be sure to follow a proper procedure for releasing the head bolts. Check the manual for proper technique. I like doing this: Start at the outer most bolts and work your way in, like a circle getting smaller, and start with less than 1/4 turns for the first 3 passes until the pressure is released. Putting the head back on, follow the torque sequence and check if they are stretch fit bolts/torque to yield or not. If they are, replacement is best. TTY have a degree they are torqued to in steps or as the final step, following an initial or build up sequence of lower torques. |
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| Author: | Sunchaser [ Sat Mar 28, 2015 12:24 pm ] |
| Post subject: | Re: 4G15 Timing Belt |
Im just going to really skimp out and see what happens. I am going to just throw a timing belt on there and see if it runs. Then ill decide what to do from there. Im thinking I should draw the line financially on this motor. Its sounding like to do the timing belt right with removing the head and machine work, valves, water pump, belts, and seals it could be like $150-$200 which seems unreasonable. The belt had no signs of cracking or anything, I feel it was a sign to push me towards a bigger engine. |
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| Author: | Flying Eagle [ Sat Mar 28, 2015 8:59 pm ] |
| Post subject: | Re: 4G15 Timing Belt |
It will run you at least that, to do minimal job but you can confirm no compression via leak down tester kit. Got a tool loan program with any local parts places? You tell very quickly and it won't cost you more than a rental, and your gas. Takes very little time. Heck you can rig up a blow gun with a rubber snubber (conical cylinder shape) and plug it up against the empty plug hole. With the motor lined to have the valves closed, try shootin in some air. You'll know if 1 or more cylinders is leakin badly. Can always pop the valve cover too. Excessive clearance/rocker arms that have massive free play will indicate valves hung open. 4g15's had adjustable rocker arms and their clearance wasn't more than .015", so an easy check by wiggling the rockers. You will without a doubt when you feel a seriously loose rocker arm set. |
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| Author: | Sunchaser [ Sun Mar 29, 2015 1:26 pm ] |
| Post subject: | Re: 4G15 Timing Belt |
I don't have an air compressor, I may pull the valve cover to check clearances. Worst case a valve or 2 is bent and I go to start it and It will just total the engine right? Best case it still runs. Plus I will learn how to time an engine and install a timing belt.. Its just a science project for me now. If the head/pistons are bad I will just pull the engine and trans and save for a 4g63, 4g64 or G4CS or maybe even try to track down a diesel Mitsubishi engine |
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