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400 Chevs First Startup, But With Problems

Started by _jabba_ , Apr 26 2008 05:51 PM

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16 replies to this topic

#1 _jabba_

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Posted 26 April 2008 - 05:51 PM

Well i started my 400 chev for the first time today, and after realising that i left a plug off my coil-in-cap dissy she fired stright into life and idled perfectly but i noticed that the oil pressure gauge was reading over 60psi at idle and when i touched the throttle and brought the revs upto what id guess was around 1200rpm the guage spiked over the max of 80 psi that the guage displays. I turned it off and then noticed a huge pool of oil on the ground, the oil filter seal blew out and spewed over 2L of oil over the ground. The oil pressure guage is now broken and reporting 40psi without anything connected :rolleyes:

.

A quick google makes me think that the pressure release valve is stuck closed but the only reference i can find to that in my chev book is the one that the oil filter screws to and that valve moves freely (i'm pritty sure thats the oil filter bypass valve). I thought it could have been built into the actual pump but i cannot see it in the exploded view pics.

Other than that it sounded soooooo tough straight off the extractors :tease:

.

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#2 _jabba_

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Posted 26 April 2008 - 07:21 PM

Any ideas would be great, has anyone had this happen before?

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#3 _Lostit_

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Posted 26 April 2008 - 09:23 PM

At cold mine shows about 50psi on start up .

At idle when warm should show about 40psi and basic rule of thumb for every 1k rpm = 10psi .. so 5krpm = 50psi etc.

Firstly get yourself a proper oil pressure gauge .. and what sort of oil you running in it ? Did you prime the pump first ?

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#4 _jabba_

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Posted 26 April 2008 - 09:44 PM

The oil is 20w - 50 repco branded oil (just for the first startup). I didnt have the priming tool for the chevs so i removed all the plugs and cranked the engine until the guage registered oil pressure, it cranked for about 4-5 seconds and then the guage reported 40 psi and climbing but i stopped cranking.

It only blew the oil filter seal when i touched the throttle, I barely moved it just to raise the idle slightly and the guage (however in-accurate) snapped past the highest reading.

Ill return the guage tomorrow and get a real one.

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#5 V-SLR5000-P

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Posted 26 April 2008 - 09:46 PM

The relief valve is in the pump, with the sump removed you will see a spring retained by a scroll pin opposite the oil pick up. This spring places pressure on the back of the relief valve and governs the maximum oil pressure. If the valve is jammed closed your oil pressure will be too high. 80+ psi is way too much and you are at risk of breaking the oil pump drive amongst other things.

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#6 Litre8

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Posted 26 April 2008 - 09:57 PM

Regardless a quality racing style oil filter, like K&N etc, should be able to handle these pressures.

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#7 _jabba_

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Posted 26 April 2008 - 10:01 PM

Sounds like the sump is coming off again then

, is it worth trying to fix this pump or do i just toss it and buy a new one? Is it common for the relief valve to stick?

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#8 _jabba_

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Posted 26 April 2008 - 10:09 PM

Regardless a quality racing style oil filter, like K&N etc, should be able to handle these pressures.

The filter i used was just your generic repco supplied job, id have to check what is is. The rubber oil seal on the filter was pushed out of its seat and if you could see it between the block and the filter.

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#9 V-SLR5000-P

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Posted 27 April 2008 - 07:21 AM

Well i started my 400 chev for the first time today

You must sort out this problem before you attempt to restart, particularly if its a new engine. It is very important to follow correct cam break in procedure as the life of your cam shaft depends upon the first few minutes running. Refer link to Crane Cams site:

http://www.cranecams.../?show=faq&id=1

You can check the oil pressure without restarting by using a priming tool or old distributor drive with an electric drill. Not recommended practice to crank on the starter to build initial oil pressure. If the problem persists take it up with your engine builder, otherwise pull out the oil pump and check the relief valve or just get another pump.
Before you go for another resart:
Fit an exhaust system, your neighbours will thank you and its easier to hear any potential problem.
Have a mate handy to check for leaks or other problems when once you start up.
Immediately bring engine revs up to 2000, and vary between 2000-3000rpm for the next 20 minutes. DO NOT IDLE.
You can break in the cam in a couple of 10 minute sessions if necessary.
After the cam break in change the oil and filter and give the engine a check over making sure that bolts remain tight and nothing is leaking, rubbing, lying on the exhaust etc.
Take your time, do it right and good luck with it!

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#10 _jabba_

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Posted 27 April 2008 - 10:23 AM

Thats fair enough, Ill order a new oil pump tomorrow because its not worth ruining the engine over such a cheap part.

Where can i buy the priming tool, i couldn't find it on fleebay australia.

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#11 V-SLR5000-P

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Posted 27 April 2008 - 12:21 PM

You can make a priming tool from an old distributor, otherwise try Repco or performance parts supplier like VPW or Superplus.

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#12 _1QUICK LJ_

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Posted 27 April 2008 - 12:49 PM

mate a 20-50 oil is far too thick for a new engine, especially when cold start up. i suggest you use a propper running in oil such as valvoline. penrite ect. its much thinner so its better when everything is closer tolerences, once everything is bedded in then change to a thicker type oil, but i wouldnt see the need for anything higher than 40w oil if everything is right. the 50w oil is for sloppy old worn engines really or race engines with big clearences. the other advantage to the running in oils is that they have a very high zinc content which is needed for proper f/t cam break in. if you are running a flat tappet cam i would also suggest using the crane cams or comp cams cam break in additive in your oil. alot of my race engines see well beyond 8000rpm with no dramas running 40w oil and 60-65lb oil pressure at peak rpm. lastly anything like a ryco or better filter should be fine. are you sure it was nice and tight if not the seal will blow out.

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#13 Struggler

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Posted 27 April 2008 - 08:41 PM

Like 1QUICKLJ said, use a straight 30W oil for break in.

Like Lostit said, get an accurate OP gauge.

The problem is NOT with the oil pump. The engine just has small clearances that will loosen up with time. OP is at its highest on a cold start.

I have had similar problems before with some cheaper oil filters. Is the oil filter O ring a round or square section ? If its round then chuck it. Ryco use a square section O ring to seal their Chev style filters, use one of them. Fill the engine with 30W run-in oil and fit an accurate gauge. Start it and follow V-SLR5000-P's cam run-in procedure if it hasn't been done already.

Hope this helps.

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#14 _jabba_

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Posted 02 June 2008 - 11:05 PM

I pulled the pump out and it looks like it was the culprit, the valve was a jammed and after i poked it with a screw driver it freed up and is now moving smoothly. It looks like there was some moisture in the pump and has corroded over the last 3 or so years its been in the engine. I take it that i should just replace the pump now its out because of the surface rust?

Damien

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#15 _jabba_

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Posted 02 June 2008 - 11:42 PM

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#16 _LX406_

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Posted 03 June 2008 - 10:54 AM

Buy a new oil pump, they are about $50 from memory. Also remember some 400 chevs have different oil filters to 350's etc. The rubber seal is a different diameter on my 400 compared to some 350 filters. I run a Ryco Z40 with no dramas.