Rebuilt engine ques
- Thread starter BigDiesel
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david85
Full Access Member
You could just try a power balence test on each injector to see if the shake doesn't get worse when you loosen each of them. If nothing else it would narrow down the problem to that exact cylinder (if it is indeed a problem that is isolated to one hole).
When I first started my engine after dropping it back in, there was some blowby (comparable to when I tore it down), but it settled into a smooth idle in seconds and waited patiently for me to take it out for a spin.
I did take the truck on some hills and did the usual hard acceleration with engine braking to slow back down. Did that for a few days in a row and kept a close eye on the pyro since you don't want the EGTs to get too high early in the break-in. I've been told it can cause a premature glazing to build up in the cylinders and prevent rings from seating. And whatever you do, don't run straight veggie oil on a break in either.
When I first started my engine after dropping it back in, there was some blowby (comparable to when I tore it down), but it settled into a smooth idle in seconds and waited patiently for me to take it out for a spin.
I did take the truck on some hills and did the usual hard acceleration with engine braking to slow back down. Did that for a few days in a row and kept a close eye on the pyro since you don't want the EGTs to get too high early in the break-in. I've been told it can cause a premature glazing to build up in the cylinders and prevent rings from seating. And whatever you do, don't run straight veggie oil on a break in either.
I am going to also try the balance test to see if one injector is at fault. The engine runs smooth other than the idle. I also want to try hooking up to a nice heavy trailer with a load on it to try seating the rings better.
icanfixall
Official GMM hand model
Cylinder glazing during breakin is from not getting the heat up in the cylinders because your driving too easy. Driving the engine up in rpm and then letting it drop down wears both sides of the rings into the cylinders. Plus it burns off the oil glaze that strats building up because your not getting the rings hot enough. Load up the truck and drive it hard. These engines are made to work. At the very least fill the bed with sand or dirt. Around 1000 or 1500 lbs works fine. Then drive it and find some hills or long grades. Watch the temps and have at it. A babied engine will never break in. Do you ever see a big rig being babied when it goes to work. I have not. They earn their money or they get replaced fast...
Todd C
Full Access Member
A second to Icanfixall 
Mine was rebuilt as an IDI Turbo. Turbo flexplate (hard to find) and Turbo harmonic balancer, as well as all the internals. It was balanced as well. It runs great, shakes only a little at idle, and smooths out real nice at speed...
Mine was rebuilt as an IDI Turbo. Turbo flexplate (hard to find) and Turbo harmonic balancer, as well as all the internals. It was balanced as well. It runs great, shakes only a little at idle, and smooths out real nice at speed...
david85
Full Access Member
Oh I agree you don't want to baby it on the break in. What I was told is that if the EGTs get too high early in the break in before the rings seat (where oil control is not yet ideal), then that can cause glazing too. I think I kept mine under 600F for the first few miles, then took it to 800F on the 3rd day or so. Seems to have worked fine
seawalkersee
It needs a turbo...
Quick question, how did you keep it below 600F? Thats a short hill for me normal driving...but I do have a baby moose.
SWS
SWS
david85
Full Access Member
Unless there is a sustained hill climb, that is my cruising temperature even up to 70 MPH. The only real hill we have close by starts off at 5% and then maxes out to 10% near the top but over all its barely more than a mile long.
Other then that, it was just a case of accelerating fast and hard for a few seconds (while still keeping the exhaust clear to prevent smoke lugging), then letting the engine slow the truck back down again several times. This allowed me to load it while keeping the EGTs in check. Diesels can cool off very fast during engine braking due to the large amounts of extra air that goes through them from lack of a trottle valve.
I'm not saying this is the way to do it though since this is only the second engine I ever built. So if those more experienced have another view, I would sooner go with that, and consider myself lucky if my method wasn't ideal.
Well I just changed injectors and the shake is alot better but still there. The bb injectors are much better than the gs in the fact they are much more responsive. The engine is much more responsive with less throttle for the same fuel output. The engine sounds completely different as well. The shake is about the same as my old n/a engine so it is manageable, and seems to get better the more I run the legs off of it. Thanks guys.
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