RedZ85 Posted December 10, 2005 Share Posted December 10, 2005 I have been playing with my 355 Chevy for a while now and had an issue i have been trying to solve. My oil pressure seems to be way to high. It seems to be around 75 PSI on a cold start...but stays there. If i rev the engine, it grows to 100...maybe more but the gauge i got to test only goes to 100. The engine is warmed and it doesnt seem to solve the problem. I have a summit 7 Qt. oil pan: http://store.summitracing.com/default.asp?Ntt=oil+pan&searchinresults=false&Ntk=KeywordSearch&DDS=1&N=115&target=egnsearch.asp and a Summit high volume oil pump: http://store.summitracing.com/default.asp?target=partdetail.asp&part=SES-3-60-08-035 Are high volume pumps suposed to generate higher pressures? If so, that high? I noticed that if i drive it for a while and drive fast with the rpm's up once or twice once warmed up...the pressure returnes to normal and remaines at around 40-50 psi. Any ideas? I dont want to really drive my Z anymore until i get this figured out. Thanks! Quote Link to comment Share on other sites More sharing options...
jt1 Posted December 10, 2005 Share Posted December 10, 2005 Sounds like the piston in the bypass valve on the pump is sticking. Drop the pan, remove the pump, disassemble the bypass valve, and make sure that the piston isn't binding or have any debris in it causing it to stick. Also, what weight oil are you running? 40 or 50 wt single vis will do that, a good 15-40 is your best bet. jt Quote Link to comment Share on other sites More sharing options...
Poundz9oh9 Posted December 10, 2005 Share Posted December 10, 2005 I had the same problem when I was running a non-bypass style oil filter adapter. I replaced it with a stock type ................ problem solved. Quote Link to comment Share on other sites More sharing options...
dr_hunt Posted December 10, 2005 Share Posted December 10, 2005 If the pump bypass was stuck, it'd blow the filter and the sender right out of the block. It might not be opening all the way, but it sure isn't stuck closed. Oil pressure depends on clearances, pressure relief spring. I run 80psi on racing engines that routinely see over 7K in circle track using a dry sump system. I think the pressure port is down system and in clean oil from the filter so it'd probably be the pump bypass. There are typically two springs, low and HP. In loose bearing clearances, typically you have to shim the spring, at least I do to get 60psi, especially when using remote filters. Quote Link to comment Share on other sites More sharing options...
RedZ85 Posted December 10, 2005 Author Share Posted December 10, 2005 Im going to check that out. The engine was built for high RPM drag racing before...Whats a non bypass adapter look like? Thanks for the ideas. Should 15-40 oil LOWER the pressure?? I would think that it would raise it. Thanks Quote Link to comment Share on other sites More sharing options...
jt1 Posted December 10, 2005 Share Posted December 10, 2005 Poundz brings up a good point about the oil filter adapter, one I didn't think of, and it would be a lot easier to check that first. A stock bypass style has a port for oil to flow thru, while a non bypass doesn't have the extra port. The bypass is the round part of the oil filter adapter at about the four o'clock position from the nipple the filter screws on to. If yours doesn't have the extra round part, it's not a bypass style, and could be the cause of the problem. Heavy weight oil will give high oil pressure while cold, then drop as it warms up. Multi vis will give less initially, but remain more constant as the engine comes to temp. I'm not suggesting the oil pump bypass is completely stuck, just that it could be binding when cold. jt Quote Link to comment Share on other sites More sharing options...
RedZ85 Posted December 10, 2005 Author Share Posted December 10, 2005 It does have the bypass port. Is there such thing as a high pressure by pass port?? I can open the valve relitivley easy with my finger. I put a new filter on before i removed this adapter, but that changed nothing. the oil pump that i have installed is brand new from summit with less that 50 miles on it...Is it still worth investigating the valve on that?? How would i test it? Im really not looking forward to droping my pan again...anything else that could cause this? This is what i have: Valve open with a bolt. I was thinking...My engine isnt all that ratical. Its 10:1 compression, Comp 256 Cam redlines at 6K and is mostly a daily driver. Would i be better off with a stock 4 qt oil pan and stock oil pump?? Thanks guys Quote Link to comment Share on other sites More sharing options...
jack46 Posted December 10, 2005 Share Posted December 10, 2005 My oil pressure seems to be way to high. It seems to be around 75 PSI on a cold start...but stays there. If i rev the engine, it grows to 100...maybe more but the gauge i got to test only goes to 100. The oil bypass is not sufficient to 'blow off' the pressure being generated. Are high volume pumps suposed to generate higher pressures? Since they flow more volume they will build pressure quicker in the same engine. In theory the relief pressure should remain the same. BUT as in your case it is not, I have had a high volume do almost the same on 30 weight. If so, that high? Mine would get to ~80 when cold and be fine once warm. I noticed that if i drive it for a while and drive fast with the rpm's up once or twice once warmed up...the pressure returnes to normal and remaines at around 40-50 psi. Well that to me says it is FINE when the system is at equilibrium so the problem is simply when cold. Any ideas? I dont want to really drive my Z anymore until i get this figured out. Thanks! Two areas the bypass system and oil weight and type. I am lazy I say go to a lighter oil. also what oil filter are you using? Also post oil in there now outside temperature or engine temp at startup etc. Im sure Grump will have a detailed answer soon. I agree wait for explanation from Grumpy before driving it. Good luck Quote Link to comment Share on other sites More sharing options...
RedZ85 Posted December 10, 2005 Author Share Posted December 10, 2005 I have to get the engine reved before the pressure drops...then sometimes, it raises back up again...this is looking more and more like a oil pump relieve valve issue... UPADATE! I pulled the oil pump. The relieve valve seems to be functioning properly. There is unrestricted movment during the entire travel path. There is a purple spring installed in the relieve valve. Is this a high pressure spring? If my pump is working correctly...why am i getting 75-100+ psi!!? Quote Link to comment Share on other sites More sharing options...
dr_hunt Posted December 11, 2005 Share Posted December 11, 2005 Typically, I knock out that little wafer and spring, tap it for 1/4" pipe and put an allen head oil galley plug in it. Don't want or need any oil filter bypass. The oil pressure sender is plumbed after the filter so I doubt if the oil filter bypass has anything to do with it. If anything it is a restriction and would lower oil pressure. It's possible that the oil pump bypass is sticking only partially open, but your not really hurting anything anyway. The detrimental part of too much oil pressure is distributor gear wear and loss of 4 or 5 hp. You hear of washing the bearings, but I've personally never witnessed that type of wear, ever. Why are your running 15W40 anyway? If you have that kind of pump I'd run 5w30 or 0w30 for better lubricating properties. Quote Link to comment Share on other sites More sharing options...
RedZ85 Posted December 11, 2005 Author Share Posted December 11, 2005 Why are your running 15W40 anyway? If you have that kind of pump I'd run 5w30 or 0w30 for better lubricating properties. Im using non synthetic 10w-30 to break in my cam...I was going to start using Mobal1 full synthetic 10w-30...but now im thinking of a thinner oil. Is the reason that i have really high pressure simply my oil? Quote Link to comment Share on other sites More sharing options...
jt1 Posted December 11, 2005 Share Posted December 11, 2005 Pretty amazing it will spike to 100+ psi on 10W30; I was expecting you to say you were running 40W or 50W. I guess your options are to run a thinner oil, or change the pump relief spring. In the pumps I have seen that come with more than one spring, the purple one is the highest pressure. A recent Canton pump came with three, plain(lowest), yellow(med), and purple(highest). You can't really say a certain spring will give a certain pressure because of variations in the clearances and oiling systems. If it was mine, I would stick with the 10W30 and try a lighter spring, even though dropping the pan is a PITA. John Quote Link to comment Share on other sites More sharing options...
MONGO510 Posted December 11, 2005 Share Posted December 11, 2005 I had a simular problem with a big block HV pump installed on a 350. I ended up using 4 Qts. of 5-30 oil and 1 Qt. of ATF. It dropped my oil pressure to an acceptable number and also kept the engine internals very clean. Quote Link to comment Share on other sites More sharing options...
Alf Posted December 11, 2005 Share Posted December 11, 2005 why don't you try hooking up a different guage, it just may be giving faulty readings. other than that the way you described your engine, it does't need a high volume oil pump, a stock replacement would do just fine. Quote Link to comment Share on other sites More sharing options...
RedZ85 Posted December 11, 2005 Author Share Posted December 11, 2005 I have a mechanical gauge installed to verify the electric gauge results Quote Link to comment Share on other sites More sharing options...
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