Rod knock - Help!
#1
02-05-2020, 12:29 PM
Rod knock - Help!
The BAD: There IS a Rod Knock. Initially thought it was coming from the top.. now seems to be coming from the middle/bottom more. (Had car up on ramps today. Put in 20W-50 motor oil. Some improvement. Knock still there.
Car still stalls when at a light and brake pedal depressed/surges. Brake booster is leaking badly, LOUD hissing sound from brakes.
The GOOD:
- I still have oil pressure (ALL of it.)
- The car drives perfectly.
WHAT I THINK HAPPENED: Aggressive induction cleaning (SeaFoam.. just with MMO. I have to say, I've done this before.. cracked a coil or two on a GMC with a Vortec 4200. Resume) led to situation to "spin a bearing;" Somehow, had one instance of the engine "racing up" to bounce off rev limiter and this knock started shortly thereafter.
Possible one cylinder "contributing poorly" .. Maybe it sucked an electrode out of a spark plug? (That happened on a previous blazer and it did pretty much exactly what mine is doing now, including occasional stall.)
What is the next thing to do?
And what are the chances the "Pull off the oil pan and change a bearing or bearings" trick will do it? Seems like its showing "5 out of 6" cylinder behavior at idle, with the gear selector in drive; it idles just fine in park with the brake pedal not depressed.
Car still stalls when at a light and brake pedal depressed/surges. Brake booster is leaking badly, LOUD hissing sound from brakes.
The GOOD:
- I still have oil pressure (ALL of it.)
- The car drives perfectly.
WHAT I THINK HAPPENED: Aggressive induction cleaning (SeaFoam.. just with MMO. I have to say, I've done this before.. cracked a coil or two on a GMC with a Vortec 4200. Resume) led to situation to "spin a bearing;" Somehow, had one instance of the engine "racing up" to bounce off rev limiter and this knock started shortly thereafter.
Possible one cylinder "contributing poorly" .. Maybe it sucked an electrode out of a spark plug? (That happened on a previous blazer and it did pretty much exactly what mine is doing now, including occasional stall.)
What is the next thing to do?
And what are the chances the "Pull off the oil pan and change a bearing or bearings" trick will do it? Seems like its showing "5 out of 6" cylinder behavior at idle, with the gear selector in drive; it idles just fine in park with the brake pedal not depressed.
#2
02-05-2020, 12:59 PM
If you can actually hear a bearing knocking, just replacing the bearing will never fix it. Crank needs ground to next undersize and the bearing bore will need re-machined.
Revving the engine after dumping seafoam through it?
Revving the engine after dumping seafoam through it?
#3
02-05-2020, 03:01 PM
Now.. I don't mean to sound like an idiot, but I am *thinking* the sound I am hearing is the knock, because it wasn't there before . This "stalls when at idle and with the gear selector in D" (it will idle just fine in P and not surge.. Weird) happened the day or so before. So, I decided to try cleaning up any errant carbon.. Brings me to where I am.
I also just cleaned up the EGR valve (made the pintle move. It had some build-up.. yeah. I pushed it down with one of the two screws and let some MMO sit on it and also Brake Parts Cleaner to clean it up, also engine side, drove a short trip twice) and it will still surge about three times and die/stall that third time.
The last Blazer I had with rod knock was much, much worse, (sounded like a conga drum. This about 5 years ago now, maybe 6?) and did the same thing.. would eventually die. Almost like it was running on 5 cylinders. That engine had NO oil pressure after replacing OPSU. The truck eventually got a new engine.
Should i have a shop do a compression test? (I also see many videos about folks take off the oil pan and replace the bearings, "If it is knocking from the bottom." I'm wondering my options. It still drives just fine if no stops are involved, though I have not really driven it since yesterday, and it is now in the garage awaiting the repairs...
Changed fresh motor oil today, thicker. Slight improvement, noise is lessened; did not go away. This engine still has oil pressure.
I have some videos of what it sounded like at its WORST to where it is at now.
#4
02-05-2020, 03:10 PM
Okay it still does this.. will see if I can find the video of the bad sound (which I hope can be fixed properly on the cheap.)
I have not driven it more than a mile since I filmed this, sounding at its worst. This was that night of the Seafoaming. (Looking for that video next.)
This is how It sounded at its worst.. 5W-30 oil in there. It has since quieted but the sound can still be heard.
https://youtu.be/q664ArssX_Q
I have not driven it more than a mile since I filmed this, sounding at its worst. This was that night of the Seafoaming. (Looking for that video next.)
This is how It sounded at its worst.. 5W-30 oil in there. It has since quieted but the sound can still be heard.
https://youtu.be/q664ArssX_Q
Last edited by 93S10TahoeLT; 02-05-2020 at 03:23 PM.
#5
02-05-2020, 03:24 PM
#6
02-05-2020, 04:43 PM
How hard is it to remove oil pan?
What year engines will fit?
Is a rebuild "that bad" from a machine shop?
Compression test ?
What year engines will fit?
Is a rebuild "that bad" from a machine shop?
Compression test ?
#7
02-05-2020, 05:24 PM
And. Let's say that something like in this video were to be done. Could the bearings then be checked that way?
#8
02-05-2020, 06:23 PM
I don't blame you for wanting to see if what you are hearing can be fixed without getting a new engine but I got a feeling that if you really have spun a bearing on one of the connecting rods, then based on what I've picked up over the years you are looking at needing a new motor. And just so you know, I've never rebuilt one of these motors. My experience includes replacing motors in other vehicles and replacing cams, heads and intake manifolds. However, I have tried to learn about the other parts and have learned a lot on this forum. This is why I would defer to the advice given by LesMeyer.
As for options, you might find that you can keep driving this for a bit until you save up the money necessary to have the motor pulled and either properly repaired or replaced. I don't know how viable of an option that would be though.
And to answer your specific questions:
As for options, you might find that you can keep driving this for a bit until you save up the money necessary to have the motor pulled and either properly repaired or replaced. I don't know how viable of an option that would be though.
And to answer your specific questions:
- How hard is it to remove oil pan? I think to remove the pan with the engine in the vehicle is near impossible, especially if you have 4wd.
- What year engines will fit? A vendor for rebuilt engines can likely answer this for you.
- Is a rebuild "that bad" from a machine shop? It depends. If you want some specific upgrades or otherwise customize the motor relative to stock, having a local shop do the work is likely your best option. But if you just want to get back on the road, it is likely better to have a new long-block ordered and have the other parts swapped by your mechanic.
- Compression test ? This might not tell you much. The cylinder with the bad rod bearing could get scored and then lose compression but you won't learn anything about the rod bearing.
#9
02-05-2020, 06:30 PM
I don't blame you for wanting to see if what you are hearing can be fixed without getting a new engine but I got a feeling that if you really have spun a bearing on one of the connecting rods, then based on what I've picked up over the years you are looking at needing a new motor. And just so you know, I've never rebuilt one of these motors. My experience includes replacing motors in other vehicles and replacing cams, heads and intake manifolds. However, I have tried to learn about the other parts and have learned a lot on this forum. This is why I would defer to the advice given by LesMeyer.
As for options, you might find that you can keep driving this for a bit until you save up the money necessary to have the motor pulled and either properly repaired or replaced. I don't know how viable of an option that would be though.
And to answer your specific questions:
As for options, you might find that you can keep driving this for a bit until you save up the money necessary to have the motor pulled and either properly repaired or replaced. I don't know how viable of an option that would be though.
And to answer your specific questions:
- How hard is it to remove oil pan? I think to remove the pan with the engine in the vehicle is near impossible, especially if you have 4wd.
- What year engines will fit? A vendor for rebuilt engines can likely answer this for you.
- Is a rebuild "that bad" from a machine shop? It depends. If you want some specific upgrades or otherwise customize the motor relative to stock, having a local shop do the work is likely your best option. But if you just want to get back on the road, it is likely better to have a new long-block ordered and have the other parts swapped by your mechanic.
- Compression test ? This might not tell you much. The cylinder with the bad rod bearing could get scored and then lose compression but you won't learn anything about the rod bearing.
I also wonder how much the backyard mechanics charge to swap an engine. Apparently, it is pretty simple to take an engine OUT on these...
I may also save up for THIS engine. What do you think!? https://www.ebay.com/itm/Remanufactu...oAAOSwAYtWITrW
At Promar there are no assembly lines during engine block remanufacturing. All engines are custom built. Each assembler does a visual inspection of the block, heads, crankshaft and all-inclusive parts prior to assembly. The Ra tester is used to check all cylinder bores, crankshaft journals and gasket surfaces. All parts such as crankshafts, bearings, cylinder bores, pistons, rings, connection rods, main saddles, lifter and camshaft bores are miced for proper size.
Each block is fitted with new full circle cam bearings, oil restrictors, relief valves, new water and oil plugs. The crankshaft is fitted in the block with new high quality bearings and each journal clearance is checked with plastigage, torqued and double-checked. New rings are then fitted in each bore to assure proper end gap. Each new piston is checked for proper clearance in each bore. The rings are installed on the piston and assembled into the bores. Each assembly is supplied with new high quality bearings and each journal clearance is checked with plastigage, torqued and double-checked. A new camshaft is then fitted into cam bearings bores and all new timing components are installed and double-checked by an assembly manager.
Cylinder heads are then installed with new head bolts and new Felpro or Victor head gaskets. The block now receives new lifters, push rods and rocker arms which are adjusted and a second check completed by an assembly manager. Each cylinder is then accurately checked for seal integrity to assure no compression or water leaks. At this point the engine is primed with special lubricant and a new oil pump. The residual parts of the gasket set are sent along with the engine. The assembly manager then conducts the final inspection of the engine.
All engines come with an installation manual. Bulletins about your specific engine are also enclosed in the packaging. Promar engines are secured onto a wooden pallet where vulnerable parts are protected from damage by corner covers. The entire block is wrapped in a durable plastic sheath to protect your engine from outside elements.
Each block is fitted with new full circle cam bearings, oil restrictors, relief valves, new water and oil plugs. The crankshaft is fitted in the block with new high quality bearings and each journal clearance is checked with plastigage, torqued and double-checked. New rings are then fitted in each bore to assure proper end gap. Each new piston is checked for proper clearance in each bore. The rings are installed on the piston and assembled into the bores. Each assembly is supplied with new high quality bearings and each journal clearance is checked with plastigage, torqued and double-checked. A new camshaft is then fitted into cam bearings bores and all new timing components are installed and double-checked by an assembly manager.
Cylinder heads are then installed with new head bolts and new Felpro or Victor head gaskets. The block now receives new lifters, push rods and rocker arms which are adjusted and a second check completed by an assembly manager. Each cylinder is then accurately checked for seal integrity to assure no compression or water leaks. At this point the engine is primed with special lubricant and a new oil pump. The residual parts of the gasket set are sent along with the engine. The assembly manager then conducts the final inspection of the engine.
All engines come with an installation manual. Bulletins about your specific engine are also enclosed in the packaging. Promar engines are secured onto a wooden pallet where vulnerable parts are protected from damage by corner covers. The entire block is wrapped in a durable plastic sheath to protect your engine from outside elements.
Last edited by 93S10TahoeLT; 02-05-2020 at 06:35 PM.
#10
02-05-2020, 11:45 PM
And. Let's say that something like in this video were to be done. Could the bearings then be checked that way?
https://youtu.be/XjXsM57FPsc
https://youtu.be/XjXsM57FPsc
Now I want to make sure my engine mounts are good so that the oil pan doesn't get cracked!