Toward the end of breakin period for my 3.4 I noticed some odd sounds. Sounded a little like dieseling or detonation. I was not able to hear it with the windows down. I also heard what I thought was an intermittent knock so I decided to go ahead an change the oil out at 400 miles. Oil looked a little too "sparkly" for normal breakin oil. I put the 5W30 in an now I have a constant knock. I was thinking - crap - spun a bearing.
Getting ready to look inside, I decided to run a compression check before I disconnected stuff. I discovered that #4 cylinder is low (120psi) and #6 cylinder is REALLY low (90psi). The other 4 are all around 160psi.
I am trying to put together a scenario that explains all of these symptoms - low compresson in two cylinders and a knock. > I guess I could have a broken ring, but would that cause a knock. > Cracked piston should give zero compression in one cylinder. > Burnt valve? > Why low compression in two adjacent cylinders. Does not appear to be head gasket > How could these destroy a bearing > Could it be the other way round - bad bearing broke something up in the cylinder area > I could be mis-reading the oil and it may just be normal post-rebuild junk in the oil and I need to start looking inside the head
I'm not an expert at this so I'm hoping those of you with more extensive experience can tell me where the best place to start looking is.
(I am really bummed.)
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09:22 AM
PFF
System Bot
TopNotch Member
Posts: 3537 From: Lawrenceville, GA USA Registered: Feb 2009
Squirt some oil in the low cylinders and retest. If the pressure comes up, it's rings. If it says low, it's valves or gasket or some other leak. Is your engine newly rebuilt, or pulled from another car?
why do you say it cant be a head gasket . easy way to see where it is going just put air to one cylinder and see if it come out the other if so then you have a blown head gasket.
why do you say it cant be a head gasket . easy way to see where it is going just put air to one cylinder and see if it come out the other if so then you have a blown head gasket.
I said that because I can't justify a blown head gasket as causing a knock. (Maybe I have more than one problem?)
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10:52 AM
engine man Member
Posts: 5309 From: Morriston FL Registered: Mar 2006
I tried to get the oil pan off last night but the motor mount is in the way. The forward head is also a b!tch to get off.
Since I have to look in the top end (head) and the bottom end (bearing) I'm going to pull the motor and take a good look. I'll keep you posted on what I find.
[This message has been edited by fyrebird68 (edited 01-28-2010).]
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08:14 AM
Scoobysruvenge Member
Posts: 550 From: Richmond Virginia Registered: Apr 2009
Did you measure the clearances of the main bearings when you installed the crank???
What’s the oil pressure???
Too tight a tolerance or too loose could have wiped a main bearing or two and causing abnormal piston and rod play or movement wearing the rings in an egg shape or even chipping or breaking the rings causing the compression to drop.
Oil in the cylinder is a good check for worn rings and compressed air is the best test for checking the quality of the valves and rings 100 lbs for 10 minutes or so, however much below 100 is the percentage of capacity as a rule of thumb. 82 lbs after 10 minutes = 82%
Some would say use a longer time line, but from my experience 10 minutes is long enough for any major issue to rear its ugly head, also remember that the cylinder when hot will seal slightly better. So if you get a number in the low 90s for a new engine don’t have a cow.
A wiped cam lobe would fail to open the valve. I would think I'd get normal compression but no power. Would it esplain the knock?
I'm just speaking from the experience ive had with my olds motors, a wiped lobe made a loud ass knocking noise which just turned out to be a funky backfire out of the intake. try pulling a plug wire on those cyls and see if the knock goes away.
How did you break-in the motor? Proper break-in (from what I have heard) for a fresh motor should be 2000-2500 rpm's for 15 minutes, then chage oil... Did you do an oil change after 15 minutes, after first start-up? You should have; all the assembly lube will clog the filter..My first oil change looked a little sparkly, second looked like clean oil...
Did you prime the motor before your first start? Did you bring the motor to red-line yet (I hope not w/ only 400 miles)? What is your oil PSI when new? And now? Did you use roller rockers? They do sound like a sewing machine at idle... Did you get any type of warranty on the motor?
All things considered, I would probably pull the motor before serious damage occures (if it hasn't already)
ALJR, thanks for the suggestions and pointers. I did pirme the oil pump prior to sart-up, assembly-lubed the lifters and cam lobes and did 20 min. break-in at 2000 rpm for the lifters and cam. An oil change followed by 400 miles of easy driving, never above 3500 rpm. Oil pressure when hot was low - 15psi or less. Stock parts all round. My motor warranty has expired. ____________________________________________________
I pulled the motor and tore into it. Current state of affairs....
> I have one or two burnt valves. Probably there when I put the motor in. Explains my low compression. I didn't check the heads because they were supposedly refurbished 9000 mi. ago by the PO. > Rod bearings show light scoring, but still usable. Clearances were in range. > Cam lobes and lifter bottoms are OK. Two were sticking. One pushrod had a metal chip stuck in it - looks like manufacturing defect. > The motor was FILTHY. After 400 miles of easy break-in driving I was able to SCRAPE sludge out of the bottom of the oil pan. I disassembled all the lifters and they were LOADED with sludge.
I have worked on a lot of clunkers and this is the worst oil I have ever seen. And it came out of a motor with 400 miles on it! I am guessing that this motor was NOT hot-tanked prior to assembly. No recourse from the supplier (Fliteline, Ft. Smith Arkansas) but they are certainly going to hear from me. I'll let you know what they say (they did not respond to my first email).
I did not find any worn parts to account for the shininess in the oil,but it could just be crap stored in the oil galleys from prior abuse of the motor.
I loosely reassembled the motor and pumped mineral spirits through it to clean the oil passages and valleys. Blew it out and cleaned everything up. Waiting on the heads to come back from the machine shop. I'll start re-torqueing the rod caps and getting ready.
------------------ Bob T.
[This message has been edited by fyrebird68 (edited 02-10-2010).]
ALJR, thanks for the suggestions and pointers. I did pirme the oil pump prior to sart-up, assembly-lubed the lifters and cam lobes and did 20 min. break-in at 200 rpm for the lifters and cam. An oil change followed by 400 miles of easy driving, never above 3500 rpm. Oil pressure when hot was low - 15psi or less. Stock parts all round. My motor warranty has expired. ____________________________________________________
I pulled the motor and tore into it. Current state of affairs....
> I have one or two burnt valves. Probably there when I put the motor in. Explains my low compression. I didn't check the heads because they were supposedly refurbished 9000 mi. ago by the PO. > Rod bearings show light scoring, but still usable. Clearances were in range. > Cam lobes and lifter bottoms are OK. Two were sticking. One pushrod had a metal chip stuck in it - looks like manufacturing defect. > The motor was FILTHY. After 400 miles of easy break-in driving I was able to SCRAPE sludge out of the bottom of the oil pan. I disassembled all the lifters and they were LOADED with sludge.
I have worked on a lot of clunkers and this is the worst oil I have ever seen. And it came out of a motor with 400 miles on it! I am guessing that this motor was NOT hot-tanked prior to assembly. No recourse from the supplier (Fliteline, Ft. Smith Arkansas) but they are certainly going to hear from me. I'll let you know what they say (they did not respond to my first email).
I did not find any worn parts to account for the shininess in the oil,but it could just be crap stored in the oil galleys from prior abuse of the motor.
I loosely reassembled the motor and pumped mineral spirits through it to clean the oil passages and valleys. Blew it out and cleaned everything up. Waiting on the heads to come back from the machine shop. I'll start re-torqueing the rod caps and getting ready.
I assume that is a typo ("break-in at 200 rpm for the lifters and cam"); should be 2000 rpm's
You definatly have an oil issue! 15psi is VERY low... I can't say exactly what yours should be; but I am using a high pressure/volume pump. Mine at idle, warmed up, is 50+psi and 70+/- when rpm's are up... If you can get a mechanical gauge to verify the oil psi is actually that low; it would make diagnosing the problem that much easier... If it is in fact that low, check to make sure all the plugs are installed in the block... Take a look at this thread of mine: https://www.fiero.nl/forum/Forum2/HTML/103890.html Lots of info about the oiling system...
I would replace ANY bearings that show ANY signs of wear. There cheap and good insurance for a long running motor...
The shinyness in the oil is most likely metal particals from your rod/main/cam bearings; from lack of proper oil psi...
BTW, sounds like the low oil pressure is the cause of your problems (aside from the valves)... Maybe check the oil pick-up tube/screen and make sure it is not too close or too far from the oil pan. using a piece of wood (of proper thickness) taped to the bottom of the screen will ensure the proper clearance...
When it is all put back together and ready to start, prime the motor w/ a drill and make sure you have more then 15psi. You will need to use the distributor body installed in the block to seal-off the rear oil passage. Otherwise, you will not build up any pressure... I know this from experiance; when I only had about 15psi because the oil was gushing out the big hose back there in the dist. opening...
Also, triple check your timing. Do not go by the mark on the dampner, rather by the piston/valve position... When I did my rebuild, I replaced the dampner with one from TFS. I transfered the marks from my old dampner to the new one. The old one must kave slipped a bit and my timing mark was off by about 15-20deg. I had to make a new mark and reset my distributor...
[This message has been edited by ALJR (edited 02-10-2010).]
You know, the low oil pressure thing's been nagging at me. I had this issue with the previous motor. This one is all new so I figured since I still saw it it must be the sending unit or the gauge. My replacement sending unit showed up the same day the motor went knock-knock.
I did due diligence in setting the pump pickup height and I have a new oil pump and screen. I don't think I'll be able to see any low pressure symptoms with the drill pump, because I only saw low pressure when the motor was hot. (BTW What big hose are you talking about by the dist. opening? I see the hole in the passage at the top of the dist. opening, but no hose...) :edit: maybe the "hose" is a figure of speech? If so, pardon my dimwitted-ness
YOur comment about timing is a good one. My first hint that I had a problem was I thought I heard detonation. I checked the timing and it was advanced. Moved it back, but I was still hearing stuff (turned out it was the knock). I will definitely check the balancer mark against true TDC, since I have the heads off. I'll do this tonight. :edit: I just checked - it is close - maybe a couple of degrees retarded at TDC.
[This message has been edited by fyrebird68 (edited 02-10-2010).]
(BTW What big hose are you talking about by the dist. opening? I see the hole in the passage at the top of the dist. opening, but no hose...) :edit: maybe the "hose" is a figure of speech? If so, pardon my dimwitted-ness
It was a typo.. Its supposed to be hole In the block where the distributor slides in, there is an oil gally hole that supplies oil to the dist. shaft & gear. The dist body has o-rings that seal up the large hole. W/O the dist. body in the block, oil just gushes out...
how long did you have you engine before you installed it....mine had a 3 year/50,000 mile warranty...i did buy the long block so don't know if that made a difference......i've listed the contact info below for the guy i dealt w/....may want to give them a call
Bill Kalinowski Phone (479) 646-4771 Fax (479) 646-2469
he seemed to be a fairly nice guy and easy to deal w/...
Even so, I haven't found anything that they could "fix" so far. Just lots of dirt. Even assuming they agreed to do something for me under warranty, by the time I crated it up and shipped it both ways I can do it myself.
My big concerns when buying a motor like this are things like cracked block, scored or bent crank, rust, etc. I haven't seen any of those type things yet. Bad bearings or shoddy prep I'll just deal with. As I said, I'm holding off on any further communication with them until I know what happened. We'll se if my efforts yield a good motor and then I'll let them know what I found. Right now I am more concerned about getting to the bottom of it and getting the car running again.
If I had to do it again, I'd buy the long block.
[This message has been edited by fyrebird68 (edited 02-11-2010).]
ANOTHER shot to the jewels... machine shop just called said the heads are worn out. Need 9 valves, guides and seats. You know what's REALLY irritating is that I have paperwork showing that these heads were redone. Either the PO got shafted or I did (maybe we BOTH did).
Anyhoo, trying to decide to get these heads redone or look for another set. If you have a set of heads I can trust, let me know.
In the block where the distributor slides in, there is an oil gally hole that supplies oil to the dist. shaft & gear. The dist body has o-rings that seal up the large hole. W/O the dist. body in the block, oil just gushes out...
