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Engine running bad after rebuild
Here we go again
In my previous posts I have explained how I cracked my D24 head and have started to look for a new one. During this time I found a head and had it machined and I lapped the valves. Adjusted the valves to pretty much exactly to what the book says. I got new stem seals, installed a new metal head gasket and tightened it correctly following the instructions it came with. But... After all this I got the car running again but it runs like shit and barely stays running without the glow plugs even with full operating temperature and has white smoke when idling even at full operating temp. When at low throttle the engine sputters and jerks so much that driving normally is impossible. Also getting it started is a chore. It starts up and revs up and stalls multiple times before getting it barely to run with the throttle. I have verified that the valve timing is correct and I have matched the mark on the injection pump as good as I could. The head gasket doesn't seem to be leaking. Liquids are not mixing. Engine feels like it has very good compression when turning by hand. It feels like the engine has been cammed because of how much the rpms jump around constantly at idle. I'm so lost with this again. The only things I can imagine it being is the pump timing because why would only messing with the head affect how the car behaves under throttle. I tried it an hour ago and the engine doesn't have nearly as much power as it had before. The acceleration took over half as long to 60 mph as it had taken before. When I looked at the pump timing mark, I am uncertain of it because it doesn't exactly match the mark on the pump frame but I can't get the marks to match any better. It looks like if I go a tooth further on the belt, it will just jump too much to the other side. Also could 1 tooth off on the pump mess it all up so bad? I really need some input on this. |
#2
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I would guess one of these two things has happened. 1) Pump is timed 180 degrees out from camshaft. Did you verify that the cam lobes for #1 cylinder are both pointing upward (#1 compression TDC) when the injection pump gear's timing is approaching the notch on the injection pump bracket? The engine will still run with timing 180 out but extremely poorly. 2) Timing is not 180 degrees out of phase, but is also not set correctly. See below. Quote:
It's not adjusted tooth by tooth -- that is much too large of an increment to achieve the needed precision. A whole tooth???? Oh yeah, it sure could. Timing is required to be EXTREMELY exact on this engine, like on any diesel without computer control. Even a fraction of a tooth out of time will make it start/run poorly, and on many engines, a full tooth off will either make it not able to start (if retarded) or risk blowing headgasket or bending connecting rods (if advanced). This is why the timing on this engine is all done with taper or friction fit, no keyways, and why the timing process and tools are so sensitive. You can't just "line up the marks and go" like on a gas engine or computerized diesel. Visual timing just doesn't work here, you *have* to use the correct locking tool for cam timing and the dial indicator for pump timing, and go through the steps in exactly the right method and order. The good news, again, is that as long as you have the necessary equipment and info, the process is easy and the engine will run perfectly afterwards.
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86 745 D24T/ZF 345k lifted 2.5" 83 764 D24T/M46 155k |
#3
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I agree that optimism is warranted here but there is one other item that we need to verify: appropriate head gasket thickness. Unless the piston protrusion was checked and correct thickness head gasket installed the OP may still encounter hard starting, lackluster performance, and poor fuel economy even after (the probable) timing issues are rectified.
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1985 744 gle d24t 1985 745 gle d24t |
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measured the piston protrusion and it was in the accepted range for the head gasket manufacturer information |
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I didn't get the tools but did a way better job at the timing and the engine runs 5 times better atleast. It runs at a constant rpm and has good power. I need to fine tune the pump but would like to get the valve timing 100% correct beforehand and I am still unsure if it is since I didn't have the right tools. So after today I have made some observations. The pump timing absolutely was the reason the engine ran so bad. I wish I could say the smoke is completely gone but no, it smokes white smoke when cold. The smoke also was reduced from filling the whole workshop with smoke to having some visible smoke. Since adjusting the timing had such an improvement already, I hope fine tuning it will make it way better. Thank you very much for your input on this. Got my hopes back up for this car. |
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Great news.
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Once you have made the final cam and injection timing adjustments using the proper instruments, that should be further reduced and the engine should run at least as clean as it did before this work. Or possibly even better than that, depending on how accurately the timing had been set before by the previous fellow.
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86 745 D24T/ZF 345k lifted 2.5" 83 764 D24T/M46 155k |
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So I need to set this clear. I have set the cam timing the way that cyl 1 has the cam lobes pointing up and in the rear there are 2 notches and I have aligned those with the head surface. The cam timing could be a little bit wrong but I don't think that could effect the engine too much. Also I didn't have the locking pin for the pump so I loosened the rear camshaft gear and held the pump in a position where the pump gear mark aligns with the mark on the pump frame, then tightened the camshaft gear which left the pump mark aligned with the pump frame mark. When fine tuning the pump, is it normal that when starting to rotate engine counter clockwise the dial indicator number doesn't rise instantly after the 0 mark on flywheel. I measured the pump timing and adjusted it and got the piston travel to 0.92mm. It was about 0.65. Although this has improved the engine, it still smokes a bit when hot. Also I still keep having this issue where the car jerks with very little throttle. This can be seen by giving just a little throttle with the clutch pressed because the rpms go up and down constantly with little throttle. I am currently thinking it could be air in the fuel system or a fault related to the pump shutoff solenoid but doubt this one but it has to be kept possibility. I have tried it without the fuel filter and it runs the same without it so it's not about that. The pump pulls fuel very well from the tank. I'm still kind of devastated by how the engine literally ran smoother with 5 cylinders before the rebuild. It has more power now but it runs kinda rough now. |
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Couple questions for you: Quote:
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Yes me too, it should only be running better. We need to go thru it methodically. It's really not that complicated but the process does require special tools and unorthodox procedures to guarantee success. Many many have tried to "cheat" and use commonly accepted mechanics practices instead and failed.
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1985 744 gle d24t 1985 745 gle d24t |
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