Sr20det engine refreshed will not keep running now need ideas - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

Moore · 08-11-2019, 11:10 AM

Looking for ideas of what to check next.

My engine was running but had started burning to much oilit's been about 150k miles since last rebuild.

I dissassembled the engine and cleaned the rings that were covered in carbon. Honed the block and reassembled using the same rings. Compression was good at 160 across all 4 cylinders before i took it apart. I studied the burning oil was from clogged oil control rings which once apart were caked in carbon and could barely move. Now that it's back together it is very difficult to start takes 10 or so cranks. Will not stay running. My compression is now 115 to 120 on all 4. Im not sure if this is low because the rings haven't reseated or that reusing them was a mager mistake

Should the engine be able to start at 120 compression?

Ive checked timing twice cams and cas are good. Engine has spark and fuel. Plugs after it only running for 15 mins are very fouled and are completely black. Is there anything else i could be missing before i tear it back down and put new rings in?

Some specs
S13 sr black top
Haltech 1000 running on map
850cc injectors
Cp pistons and rings

Alisaihin · 08-11-2019, 03:41 PM

I'd guess reusing those rings is probably a big part of why you have a compression issue.

S14rebuild · 08-11-2019, 06:10 PM

Should of replaced the rings when you had it apart.....that is your issuse...nothing eles

Moore · 08-12-2019, 04:16 AM

Quote:

Originally Posted by S14rebuild

Should of replaced the rings when you had it apart.....that is your issuse...nothing eles

i have accepted that as well. Was looking for confirmation that the low compression readings is why it's running like shit.

What is it that makes used rings not reseal? Once cleaned they looked fine and still had lots of spring tension.

S14rebuild · 08-12-2019, 06:52 AM

Could of been reinstalled improperly....dont know without looking at it, but id just order a new set, tear it down and redo it. Chaulk it up to a learned lesson

Kingtal0n · 08-12-2019, 07:53 AM

I had a motor with 125psi across the board, ran fucking great for years like that.

I'm not saying your rings aren't an issue. I don't know honestly could go either way. Probably should not have honed the block if you are going to re-use the rings though. fwiw do a LEAKDOWN test using a quality gauge, see where the compression goes.
But it sounds like you have the cam timing wrong, if it isn't the rings.

also as an aside. Oil control and oil burning tells me the pcv system probably isn't connected properly.
Almost all engines are like that, and I used to think the sr20 was the most sensitive to improper pcv until I started reading about LS engines and their idiot oil control owners

*brndck* · 08-12-2019, 09:44 AM

+1 for do a leakdown test

i'm saying 90% chance its your ring gap being wayyyyyyyyy too large now

Moore · 08-12-2019, 02:39 PM

I don't have equipment for a leak down test but i did do a wet comp test and comp jumped up to 150 so im confident the compression is from rings not gasket or valves.

I kept thinking the problem was timing as well but i poped the valve cover off and double checked and everything's lined up properly.

As for pvc i agree i think that was a cause of my issues. I think when you run higher boost when you jump off throttle a lot of oil gets pulled through the valve into the manifold it had a nice coating.

Pvc was also part of my refresh. I now put the pvc to a catch can. I also ditched using my intake as the source of vacuum in boost and went to an exhuast set up with a check valve. Also ditched the t fitting and welded the buying on to the top of the valve cover. In heinsigth i probably should have done this before cleaning up the pistons but oh well shit happens. Going to start pulling it all back apart tonight

Kingtal0n · 08-13-2019, 12:42 PM

Eh

PCV using exhaust drive suction is effective... if you have the check valve placed properly, and there is no backpressure in the exhaust. When using a turbo it generally means you can't use a muffler.

Next the catch can is for hurt engines which blow oil, I wouldnt want one or run one at all. If there is an issue pulling oil into the intake that is a baffle problem, it shouldn't do that.

I've written half a book across the internet about that. Ill post some links when I get a chance

08-11-2019, 11:10 AM	#1
Moore Leaky Injector Join Date: Nov 2004 Location: toronto Posts: 67 Trader Rating: (0) Feedback Score: 0 reviews	Sr20det engine refreshed will not keep running now need ideas Looking for ideas of what to check next. My engine was running but had started burning to much oilit's been about 150k miles since last rebuild. I dissassembled the engine and cleaned the rings that were covered in carbon. Honed the block and reassembled using the same rings. Compression was good at 160 across all 4 cylinders before i took it apart. I studied the burning oil was from clogged oil control rings which once apart were caked in carbon and could barely move. Now that it's back together it is very difficult to start takes 10 or so cranks. Will not stay running. My compression is now 115 to 120 on all 4. Im not sure if this is low because the rings haven't reseated or that reusing them was a mager mistake Should the engine be able to start at 120 compression? Ive checked timing twice cams and cas are good. Engine has spark and fuel. Plugs after it only running for 15 mins are very fouled and are completely black. Is there anything else i could be missing before i tear it back down and put new rings in? Some specs S13 sr black top Haltech 1000 running on map 850cc injectors Cp pistons and rings

08-11-2019, 03:41 PM	#2
Alisaihin Join Date: Dec 2014 Location: Iowa Age: 28 Posts: 32 Trader Rating: (0) Feedback Score: 0 reviews	I'd guess reusing those rings is probably a big part of why you have a compression issue. __________________ Beep beep signature here

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08-11-2019, 06:10 PM	#3
S14rebuild BANNED Join Date: May 2019 Location: Florida-FAIL Posts: 2,497 Trader Rating: (8) Feedback Score: 8 reviews	Should of replaced the rings when you had it apart.....that is your issuse...nothing eles

08-12-2019, 06:52 AM	#5
S14rebuild BANNED Join Date: May 2019 Location: Florida-FAIL Posts: 2,497 Trader Rating: (8) Feedback Score: 8 reviews	Could of been reinstalled improperly....dont know without looking at it, but id just order a new set, tear it down and redo it. Chaulk it up to a learned lesson

08-12-2019, 07:53 AM	#6
Kingtal0n Post Whore! Join Date: Jul 2005 Location: South Florida Age: 38 Posts: 4,649 Trader Rating: (17) Feedback Score: 17 reviews	I had a motor with 125psi across the board, ran fucking great for years like that. I'm not saying your rings aren't an issue. I don't know honestly could go either way. Probably should not have honed the block if you are going to re-use the rings though. fwiw do a LEAKDOWN test using a quality gauge, see where the compression goes. But it sounds like you have the cam timing wrong, if it isn't the rings. also as an aside. Oil control and oil burning tells me the pcv system probably isn't connected properly. Almost all engines are like that, and I used to think the sr20 was the most sensitive to improper pcv until I started reading about LS engines and their idiot oil control owners

08-12-2019, 02:39 PM	#8
Moore Leaky Injector Join Date: Nov 2004 Location: toronto Posts: 67 Trader Rating: (0) Feedback Score: 0 reviews	I don't have equipment for a leak down test but i did do a wet comp test and comp jumped up to 150 so im confident the compression is from rings not gasket or valves. I kept thinking the problem was timing as well but i poped the valve cover off and double checked and everything's lined up properly. As for pvc i agree i think that was a cause of my issues. I think when you run higher boost when you jump off throttle a lot of oil gets pulled through the valve into the manifold it had a nice coating. Pvc was also part of my refresh. I now put the pvc to a catch can. I also ditched using my intake as the source of vacuum in boost and went to an exhuast set up with a check valve. Also ditched the t fitting and welded the buying on to the top of the valve cover. In heinsigth i probably should have done this before cleaning up the pistons but oh well shit happens. Going to start pulling it all back apart tonight

08-13-2019, 12:42 PM	#9
Kingtal0n Post Whore! Join Date: Jul 2005 Location: South Florida Age: 38 Posts: 4,649 Trader Rating: (17) Feedback Score: 17 reviews	Eh PCV using exhaust drive suction is effective... if you have the check valve placed properly, and there is no backpressure in the exhaust. When using a turbo it generally means you can't use a muffler. Next the catch can is for hurt engines which blow oil, I wouldnt want one or run one at all. If there is an issue pulling oil into the intake that is a baffle problem, it shouldn't do that. I've written half a book across the internet about that. Ill post some links when I get a chance