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| Replaced a bad hydraulic lifter, and now no compression when turning over https://slantsix.org/forum/viewtopic.php?f=19&t=63277 |
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| Author: | 62alumblock [ Sat Feb 09, 2019 11:29 am ] |
| Post subject: | Replaced a bad hydraulic lifter, and now no compression when turning over |
The saga continues!! I just replaced a bad hydraulic lifter. The number 6 intake valve's rocker arm and spring were making an awful tapping sound (I listened with a tube to confirm this was the source of the noise) so I got a replacement lifter. The engine is from the junkyard, I was told it was a 70s model from a truck, but since it has these hydraulic lifters it must either be an aftermarket upgrade, or actually an 80s year engine. Anywayz, I removed the rocker arm assembly, pulled out the bad lifter (I could depress the plunger in this lifter, the other 11 I could not), and then popped in another lifter that I got from the auto parts store. It looked to be almost the same specs as the bad one. Then put the rocker arm assembly back on, and it seemed like the springs were depressed a little further than I had noticed before. I try to start the engine, and it sounds like there is no compression whatsoever. I can spin the engine relatively easily. Is there anything I could have done in the replacement of the lifter to cause the cam and the crank to fall out of time? I checked and it seems like I am at TDC on #1 when the timing mark is where it should be, and the #1 rocker arms are slightly loose (I can jiggle them back and forth a couple of hairs) telling me that they are not putting pressure on the valves so I should be on the compression stroke). The rotor points to #1 at this point as well. This tells me I should be have compression. Will one open valve cause no compression through the entire engine? Now, I just got this engine going after a putting a new timing chain and cam sprocket on the thing. The old chain jumped because the sprocket's screw was loose, allowing the sprocket to turn a little. I could turn the harmonic balancer back and forth and there we a lag between it moving and the rotor moving. I replaced those, and got the car running. It was actually running very good, just with the tapping sound. There is a chance the sprocket is loose again, but there is no lag between rotor and balancer, and the timing/combustion seem to be aligned, so I am really hoping that is not the case because I really don't want to get to that timing chain again. Ok, please tell me there is an obvious fix here. Oh, I did pre-load the lifter with oil, just a little to stiffen the thing up before I dropped it in. I read conflicting statements on this online. Maybe it's at max extension now, or something like that...... thanks again for anyone's input. |
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| Author: | GregCon [ Sat Feb 09, 2019 11:36 am ] |
| Post subject: | Re: Replaced a bad hydraulic lifter, and now no compression when turning over |
One cylinder with an open valve and no compression won't prevent an engine from starting and running. The engine 'sounds' like it has no compression? What does the compression gauge say? The timing chain/cam won't affect compression either in this situation. Even if you have no timing chain at all, the engine will still have compression. You're missing something...not sure just what but you are overlooking something. Sounds more like no spark. |
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| Author: | sixinthehead [ Sat Feb 09, 2019 11:52 am ] |
| Post subject: | Re: Replaced a bad hydraulic lifter, and now no compression when turning over |
Hydraulic lifters can extend when the pushrods are removed, and then sometimes it takes them a while to collapse back to the proper preload so they end up holding the valves open. You did mention that the springs seemed compressed more than before. I have had this happen on many different kinds of engines. Sometimes if you just wait a day or so they will relax, and other times spinning the engine over with the plugs out (don't fry the starter) helps them bleed down. Your engine may have sat for a while, and so I bet everything is going to be a little sticky at first. Frequent oil changes for the first few thousand miles with good oil (maybe even a little Marvel if you like that kind of thing) might help it out. |
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| Author: | 62alumblock [ Sat Feb 09, 2019 12:29 pm ] |
| Post subject: | Re: Replaced a bad hydraulic lifter, and now no compression when turning over |
It started!!! It's running great with no tapping sound. Though, it's running hot. Does anyone know if this 80s model head does not match up with my 62 temp gauge? I just gave it a test drive, and after it cooled a little took the radiator cap off, then put a thermo-meter in it and it's at 200F. The gauge in the care is about 1/8" from being in the red. It was a little cooler when driving, like a little more than half way to red. The thermostat seems to be working, as hot water is in the upper hose. |
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| Author: | DadTruck [ Sat Feb 09, 2019 7:23 pm ] |
| Post subject: | Re: Replaced a bad hydraulic lifter, and now no compression when turning over |
Agree with your assumption, most likely cause is the temp sensor changed. |
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