Oil pressure relief, oil cooler, and accusump interaction Options

[Seabird]

Good morning everyone. I am in the process of upgrading my oil system. This is on my dedicated track 914. The upgrades include remote oil cooler, accusump, and CB Maxi oil pump.

In my research for installing the accusump it seems like there are two places that are recommended, in the cooler return line with a check valve and direct to the block. I did not want to use the sandwich plate adapter so I opted for the block option. Simpler with less seals to fail.

As I looked into the workings of the type IV oil system I found a potential problem with both these locations; the oil relief valve on the front of the engine. VW used this valve to bypass the cooler when the oil is thick. But this also means the cooler is bypassed when the oil pressure is high. Does the use of an oil accumulator negate the oil cooler system by maintaining oil pressure?

While on the straights the pump could potentially make 50-60 psi of oil pressure. (the 30mm pump that was in the engine produces those pressures much of a 20 min session) At those oil pressures the cooler will be bypassed based on what I know of the relief valve (bypassing cooler at 60psi, partially open at 35 psi, and sealed at 12psi). The accusump will also build up to that pressure. When I go to brakes and the revs drop the accusump will start pushing back and keep the pressure up till the differential is corrected. If I am back on to the next straight in that time then the pump starts building the pressure again.

Options:

1. Am I making a mountain out of a mole hill? Leave it alone.

2. Plug that relief valve so it stays closed and let the oil cooler thermostat bypass the oil when its cold. This is a pre 76 case so there is the secondary relief valve by cylinder 1. Might be able just to invert the piston so the bypass grove is below the bypass passages.

3. There is also the high pressure pistons sold by pelican parts and others. Does this just shift the bypass window to a higher pressure range?

I would love to hear people's thoughts on this.

Miguel

[ChrisFoley]

1. Am I making a mountain out of a mole hill? Leave it alone.

I think this is one of the problems that hasn't been truly solved yet, so no, not making a mountain out of a molehill.

2. Plug that relief valve so it stays closed and let the oil cooler thermostat bypass the oil when its cold. This is a pre 76 case so there is the secondary relief valve by cylinder 1. Might be able just to invert the piston so the bypass grove is below the bypass passages.

You can't run the engine without some kind of relief valve in the oil circuit.
Full pressure produced by the pump with cold oil will pop galley plugs.
An adjustable pressure relief valve mounted on the side of the block, with a short hose going back to the sump, would take care of it.

3. There is also the high pressure pistons sold by pelican parts and others. Does this just shift the bypass window to a higher pressure range?

That's exactly what it does.

[Seabird]

Chris,

Seems like you and I are the only ones actually interested in the subject.

BTW motor is back in and I'll be mounting the cooler later this week. I order the high pressure kit from PP yesterday. Going to be in Daytona for a Chumps race this weekend so get her running before next week is not going to happen.

Miguel

[Randal]

Chris,

Seems like you and I are the only ones actually interested in the subject.

BTW motor is back in and I'll be mounting the cooler later this week. I order the high pressure kit from PP yesterday. Going to be in Daytona for a Chumps race this weekend so get her running before next week is not going to happen.

Miguel

Not the only ones:

The bottom "T" line is to the Accusump.

[Jetsetsurfshop]

Chris,

Seems like you and I are the only ones actually interested in the subject.

BTW motor is back in and I'll be mounting the cooler later this week. I order the high pressure kit from PP yesterday. Going to be in Daytona for a Chumps race this weekend so get her running before next week is not going to happen.

Miguel

New motor?
Oh, are you driving in Chump?

[Seabird]

Thanks for jumping in Randal! I was just (IMG:style_emoticons/default/poke.gif) at folks (IMG:style_emoticons/default/wink.gif)

I guess I could have been clearer with my original post. Where the accusump input is isn't the problem; its the oil relief valve that acts to bypass the cooling loop. Oil pressure above 35psi will essentially cut the flow to the cooler. Hot oil goes directly to your crank and gets hotter.

An accusump works as an oil pressure dampener. If the oil pressure stays above 35 psi the cooler never gets a chance to cool the oil. At some point viscosity gets critically thin and then it starts passing through the cooler. But this might be to late; the oil might already be burnt or below a healthy viscosity.

Its apparently a common problem when using a 30mm pump. I had no I idea at the time but my first trip to the track with my 914 resulted in this. After a 20 min session on track, driving through the pits my oil pressure warning light would come on at idle. I had to keep the revs up just to maintain 10-15 psi! A little stressful. When I checked my oil the dipstick looked completely dry!! It was so thin it would not cling to the dip stick. I freaked out and added 3qts to the motor. When I checked again after a few minutes the dipstick showed 3qts high! I had to drain off the excess oil which was black after just one session (it was new oil with zero miles before the session.)

I am just piecing the puzzle together now that I am researching the inner workings of the oiling system. (914 noob here (IMG:style_emoticons/default/biggrin.gif) )

And no my oil temp gauge was not functioning. An issue that is being resolved currently.

There is a thread on the Samba from a while back that covers the high pressure pump issue well. Its for VW 1600 motors but their oiling system and the type IV are very similar. Check it out here >>> Duel relief oiling system

I have since swapped out the 30mm pump for a 26mm pump. But I am worried that the accusump will cause the same issue.

Hopefully I was a little clearer this time.

Regards,

Miguel

[Seabird]

New motor?
Oh, are you driving in Chump?

Same motor. Had to drop it to tap the galley for the accusump. I bought a remote cooler kit from Chris and wanted to update and check a few things before going back out with it. Turns out there is an 86b cam in it. Apparently that's a cool cam. Once I finish the job I'll put together a little write up for it.

No not driving this weekend. My last experience with Chump put me off the organization. Hopefully this weekend will make me feel better about them. The race I attended was basically a 25hr demolition derby. It was crazy. They actually red flagged the race at 8am to yell at all the drivers. "Stop hitting each other or we will end the race" was the short of it.

My e30 buddies built an e30 for Chump. I have been working with them on it and this will be its first race. If it looks sane maybe I'll run a few races with them.

Miguel

[Randal]

Thanks for jumping in Randal! I was just (IMG:style_emoticons/default/poke.gif) at folks (IMG:style_emoticons/default/wink.gif)

I guess I could have been clearer with my original post. Where the accusump input is isn't the problem; its the oil relief valve that acts to bypass the cooling loop. Oil pressure above 35psi will essentially cut the flow to the cooler. Hot oil goes directly to your crank and gets hotter.

An accusump works as an oil pressure dampener. If the oil pressure stays above 35 psi the cooler never gets a chance to cool the oil. At some point viscosity gets critically thin and then it starts passing through the cooler. But this might be to late; the oil might already be burnt or below a healthy viscosity.

Its apparently a common problem when using a 30mm pump. I had no I idea at the time but my first trip to the track with my 914 resulted in this. After a 20 min session on track, driving through the pits my oil pressure warning light would come on at idle. I had to keep the revs up just to maintain 10-15 psi! A little stressful. When I checked my oil the dipstick looked completely dry!! It was so thin it would not cling to the dip stick. I freaked out and added 3qts to the motor. When I checked again after a few minutes the dipstick showed 3qts high! I had to drain off the excess oil which was black after just one session (it was new oil with zero miles before the session.)

I am just piecing the puzzle together now that I am researching the inner workings of the oiling system. (914 noob here (IMG:style_emoticons/default/biggrin.gif) )

And no my oil temp gauge was not functioning. An issue that is being resolved currently.

There is a thread on the Samba from a while back that covers the high pressure pump issue well. Its for VW 1600 motors but their oiling system and the type IV are very similar. Check it out here >>> Duel relief oiling system

I have since swapped out the 30mm pump for a 26mm pump. But I am worried that the accusump will cause the same issue.

Hopefully I was a little clearer this time.

Regards,

Miguel

That link has excellent documentation.

[ThePaintedMan]

Hey Miguel,
I don't have much to offer regarding the cooler, etc. unfortunately. But I will be at Daytona this weekend. I'll be racing with the gunmetal grey Mustang. Come by and say "hi" when you get a chance!

What does your e30 look like? I drove one at Sebring last year - those things are bulletproof, easy to drive and pretty quick. I was very impressed, other than the loose seat bolts and shock bolt that fell out going through turn 1. Stupid guys prepping the car - needless to say I won't be racing with them ever again. (IMG:style_emoticons/default/dry.gif)

[Seabird]

Ill look for you George. Look for a PM from me with contact info.

Condor Speed Shop and MAD Motorsports are the two teams that I work/hang out with. You wont be able to miss the MAD trailer; its a 53' car hauler with MAD vinyl all over it.

Here is the car:
(IMG:http://www.914world.com/bbs2/uploads_offsite/dl.dropboxusercontent.com-16683-1400672291.1.jpg)

[rmdinmd]

Ok so if I follow this right, I either already have the booster kit in or need it.

I will run just under 35 psi at around 220 degree at 60 mph. After several hours of this it has climbed to 260 degrees when I stopped to eat and let it cool down.

So I might be ahead of the game to add the booster kit and already plan on adding another oil cooler for additional cooling.

[ChrisFoley]

I've been doing a little noodling on this, and even machined into a crankcase to see inside the relief bore.
I'll post pics when I have an opportunity.
One interesting bit of evidence is a wear pattern in the bore from the spring which shows where the piston resided most of the time.
It was typically being pushed down by the oil pressure far enough to expose the cooler bypass opening.

Simply increasing the pressure resistance by using a longer piston/spring only moves the problem to a higher pressure but does nothing to solve the basic problem of oil bypassing the cooler at operating rpm.

However, there appears to be a simple "drop-in" solution which I can test in the next week or two.
My solution replaces the pressure relief piston and spring, but not with just a different piston/spring.
I plan to make a sleeve which blocks off the cooler bypass circuit, but not the sump return circuit.
The sleeve will hold a smaller diameter piston/spring designed to bypass anything more than about 60psi back to the sump.
That way the cooler will always get oil flow but never see pressure above 60psi.

[stugray]

You are not the only one interested:

http://www.914world.com/bbs2/index.php?showtopic=217063

And:

http://www.914world.com/bbs2/index.php?sho...oler&st=240

By running the oil cooler off of the oil filter bracket, I dont have the issue with it being bypassed at higher pressures.
I am also planning on running an accusump, just havent gotten to it yet.

(IMG:http://www.914world.com/bbs2/uploads_offsite/i366.photobucket.com-10819-1389661344.7.jpg)

[Seabird]

You are not the only one interested:

http://www.914world.com/bbs2/index.php?showtopic=217063

And:

http://www.914world.com/bbs2/index.php?sho...oler&st=240

By running the oil cooler off of the oil filter bracket, I dont have the issue with it being bypassed at higher pressures.
I am also planning on running an accusump, just havent gotten to it yet.

Your right Stugray, the sandwich plate adapter solves the problem of the cooler bypass. Once I eliminated the sandwich plate from possible solutions I might use I did not spend much energy on its functionality.

I have read the second thread but for some reason the first one had not come up in my searching. I did a quick read through and am going to give it a more through read through when I have a free moment this afternoon.

Thanks for chiming in.

Miguel

[Seabird]

I've been doing a little noodling on this, and even machined into a crankcase to see inside the relief bore.
I'll post pics when I have an opportunity.
One interesting bit of evidence is a wear pattern in the bore from the spring which shows where the piston resided most of the time.
It was typically being pushed down by the oil pressure far enough to expose the cooler bypass opening.

Simply increasing the pressure resistance by using a longer piston/spring only moves the problem to a higher pressure but does nothing to solve the basic problem of oil bypassing the cooler at operating rpm.

However, there appears to be a simple "drop-in" solution which I can test in the next week or two.
My solution replaces the pressure relief piston and spring, but not with just a different piston/spring.
I plan to make a sleeve which blocks off the cooler bypass circuit, but not the sump return circuit.
The sleeve will hold a smaller diameter piston/spring designed to bypass anything more than about 60psi back to the sump.
That way the cooler will always get oil flow but never see pressure above 60psi.

Great Chris! Let us know how it goes. Put me down for one when you get it worked out.

Miguel

[ChrisFoley]

Here's a little visual aid:

Relief valve components installed.


Notice the wear from the spring.


Relief piston in the closed position.


Relief piston positioned where spring marks begin. Shows cooler bypass open.

[ChrisFoley]

Here's my prototype pressure relief which eliminates the cooler bypass.
The opening pressure is estimated at 60 psi. Fine tuning may be necessary, and is done by varying the piston length to change spring preload.
Added features not shown include an o-ring seal at the top, and a screw to retain the spring.
The head of the screw will double as an alignment feature so the bypass holes line up correctly. (weld build-up visible was intended as the alignment feature)

[ChrisFoley]

I think we have a winner here!
(IMG:style_emoticons/default/smilie_pokal.gif)

We just ran the first test in an engine and the results are exactly what I had hoped for. (IMG:style_emoticons/default/smile.gif)

[carr914]

Ill look for you George. Look for a PM from me with contact info.

Condor Speed Shop and MAD Motorsports are the two teams that I work/hang out with. You wont be able to miss the MAD trailer; its a 53' car hauler with MAD vinyl all over it.

Here is the car:
(IMG:http://www.914world.com/bbs2/uploads_offsite/dl.dropboxusercontent.com-16683-1400672291.1.jpg)

Get in the car for Chump @ Sebring! George will be Driving, I will be Driving!

Of course you will be driving for 2nd Place!

[Seabird]

I just might.

Though this should get its own OT topic I'll give a short blurb here. We finished 6th at Daytona, two of our drivers had never been on the track before, and one of our drivers developed a fever while driving his stint. Had it not been for two silly penalties we would have been in the hunt for 1st place (15 min worth of penalties at sub 2:30 laps makes up the 6 lap differential at the end.) GRRRR.

Not bad for a team and car's first race! We are quite ecstatic to say the least!

Also I got to meet the George, the PaintedMan; which was cool.

OT race report over.

Mean while back on the 914 front I am excited for Chris's new solution to the oil cooler bypass issue! A week and a half away from getting to test it! Man its going to be hot at Sebring too!

Regards,

Miguel