I replaced rockers and rods. Torque to 19 foot pounds and reassembled. Tried to start and engine just spun over. No major problems with engine prior to starting this project just the common rocker knock but I will say I added new plugs. Check them for fire. All good and put original plugs back in to double check tested electrical on fuel injectors, and all those tested good. I bought a second kit from a different company And still no start. I measured with my calipers from the top of the spring cap to the engine block and with the new rockers, they compressed the springs 1/10 to 2/10 of an inch further down than the original rockers. I used the same push rods for this experiment With the new rockers. I tested compression on cylinders and found 0 to 90 psi.reinstalled all originalrockers now thoroughly mixed up still using the same rods and engine fires off, but of course smokes. The second kit measured the same 1/10 to 2/10 more spring compression than the original rockers. These were both eBay orders. Should I go with OEM to solve this or what else could be going on?
Changed rockers and rods now engine won't start
- Thread starter Mseal
- Start date
Aftermarket parts can sometimes have different specifications than OE parts, even if they look similar. The extra spring compression could lead to inadequate valve seating, causing a loss of compression. Since you noted a significant difference in compression when using the new rockers, it might be a good idea to stick with OEM parts for the best compatibility.
Given that you’re experiencing differences in spring compression, it's worth checking if the push rods are the correct length for the new rockers. If the rods are too short or too long, it can cause valve timing issues, leading to poor engine performance or no start.
In addition, make sure that the rocker arms are properly adjusted. If they’re too tight or too loose, you might not be getting the full range of motion needed for the valves to seat correctly, which can impact compression and engine start.
Also, if you disassembled the engine to replace the rockers and rods, make sure the timing hasn’t been altered. A misaligned timing chain or belt can prevent the engine from starting, even if everything else seems in order. Always start with the simplest explanation!
Even though you’ve checked the injectors, it might also be helpful to double-check fuel pressure and delivery, just to rule out any issues there. Occam's Razor is a real thing!
If you’ve returned to the original rockers and the engine fired (albeit with smoke) it’s a strong indication that the new parts are not a correct fit for your engine. Going with OEM rockers might be your best bet to ensure everything operates as it should. Also, keep an eye on that smoke – it might be oil burning off if the valves weren't seating properly with the aftermarket setup.
Good luck, and let us know how it turns out!
You have oil filled (hydraulic) lifters. When you take them out or change the rods the lifter pan will change (rise) and cause the valves to stick open. The lifters are designed with a sort of acheck valve so the oil only goes one way. It takes a little time for it to go back down and allow the valves to close. Until this occurs you motor will sound like it is simply turning over without spark plugs in it.
Since this was posted on Thursday, it should be ready to roll.
Since this was posted on Thursday, it should be ready to roll.
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