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Rothsport Anti-Drainback / Check Valves on Oil Return Line
So I thought I'd post about a positive experience on an aftermarket product. At least so far.
As you can see in the "tang" 71 car build link in my sig, we built this 2.8L engine and it's been full running and operational for a little over a year. Everyone knows that mag cases leak. Of course, when building this, everything / all the tricks were done, all the right machining, seals, parts, bits, lots of later model stuff, and even some modern car parts. I knew it would still leak. Ask any builder.
Unfortunately I can't drive the car every day. So the car will drip a little bit when sitting. I had the car in for its annual go-over, engine / car got a clean bill of health, all fluids, plugs etc changed and inspected. The car is running great.
I asked them to source the leaks. Well, some 'seeping' at the front and rear main seals, thats it, rest is dry. And it will not drip when started and driven. It didn't drip at all while at the shop for the week. And it doesn't leak or seep while running. Only while sitting. So that's good. They suspected, as none of the old cars have these check valves, the modern mezger engines DO have one on the oil tank. They suggested we try one of these Rothsport valves to stop the back flow from the tank into the sump and filling up the case.
yeah Steve Weiner just to talk about this all the time ... especially for the cars that are winter stored, there is a real possibility of the entire tank running back into the crankcase.. Some people eben suggest removing plugs and cranking to make sure there is no il in the cylinder when you hot the key and bending a rod.
I had forgotten about that till now so now im considering it.. where does it physically go ? do you have to cut into an oil line or something ?
@Spyerx very interesting! So, the majority of the oil sits in the tank? What happens when you remove the drain plug at the bottom of the case? Now less comes out?
@Spyerx very interesting! So, the majority of the oil sits in the tank? What happens when you remove the drain plug at the bottom of the case? Now less comes out?
What happens if the check valves fail closed?
i imagine about 2 litres, which is what I normally get when i change the oil. I cant see it getting stuck, it has good lubrication
@Spyerx very interesting! So, the majority of the oil sits in the tank? What happens when you remove the drain plug at the bottom of the case? Now less comes out?
What happens if the check valves fails closed?
Well, the case plug will drain whatever is sitting in the sump, so possibly less as more is retained in the tank. The car still took the same amount of oil, as you fill at idle and oil is circulating.
If the check valve failed closed you're fk'd. :-) I guess? Not sure how likely this is, it's a really simple design.
My car came with one of the Rothsport valves for the S pipe. Did not prevent smoke on startup when my valve guides were shot.
One major caution: when you rebuild an engine, if you use one of these, you ABSOLUTELY have to prime the oil pump and get some oil into the sump, perhaps via the crankcase vent. If you don't the valve will not open because the oil pump pulls fluid but not air. I found this out when I went to restart my rebuilt engine. Test cranking with no spark or fuel and I got zero oil pressure. All 10 quarts of break-in oil were stuck in the oil tank, behind the check valve. No harm done since I didn't try to fire it.
I had to drain the oil tank, get a new S hose, remove the check valve, and all was good. I probably could have dumped a quart or 2 down the breather but didn't know it at the time. I bench tested the check valve and it works fine, but ...if this fails closed, your motor will be toast.
If you use one, my understanding is that you should idle your car a bit when parking to return as much oil to the oil tank as possible.
Now with my rebuild, I never smoke, so the valve is sitting in my parts cabinet.
Just my 2c, but those seals should not leak if done right, and they are under more pressure when running than not, so seeping only when parked seems pretty odd. I would check other seals or, perhaps it's seeping all the time and you can't see it when it's running because it's cooking off the headers or dripping onto the ground. There is a huge difference between a #8 bearing seal leak and an intermediate shaft cover leak in terms of difficulty in fixing.
My car came with one of the Rothsport valves for the S pipe. Did not prevent smoke on startup when my valve guides were shot.
One major caution: when you rebuild an engine, if you use one of these, you ABSOLUTELY have to prime the oil pump and get some oil into the sump, perhaps via the crankcase vent. If you don't the valve will not open because the oil pump pulls fluid but not air. I found this out when I went to restart my rebuilt engine. Test cranking with no spark or fuel and I got zero oil pressure. All 10 quarts of break-in oil were stuck in the oil tank, behind the check valve. No harm done since I didn't try to fire it.
I had to drain the oil tank, get a new S hose, remove the check valve, and all was good. I probably could have dumped a quart or 2 down the breather but didn't know it at the time. I bench tested the check valve and it works fine, but ...if this fails closed, your motor will be toast.
If you use one, my understanding is that you should idle your car a bit when parking to return as much oil to the oil tank as possible.
Now with my rebuild, I never smoke, so the valve is sitting in my parts cabinet.
Just my 2c, but those seals should not leak if done right, and they are under more pressure when running than not, so seeping only when parked seems pretty odd. I would check other seals or, perhaps it's seeping all the time and you can't see it when it's running because it's cooking off the headers or dripping onto the ground. There is a huge difference between a #8 bearing seal leak and an intermediate shaft cover leak in terms of difficulty in fixing.
my understanding of this is a little bit different.. I dont have a 3.2 so forgive me if i speak incorrectly.
Whether you have a valve or no valve, the oil in the head will leak past the worn valve guides and down into the combustion chamber, that area should never be devoid of oil no mater what, so even if you have a check valve in there the hot oil in that head is going to start to run down as soon as you shut off the engine, obviously overnight more will run down so blue smoke in the morning.
I thought that main function of the valve was to prevent hydrolocking of the engine, and blue smoke caused by excessive oil in the crankcase seeping by the rings due to the horizontal low placement of the cylinders. over extended period if enough leaked back i would imagine a lot of oil would sep by the rings and in storage could fill it up , being very bad, or mid term cause blue smoke by creeping past the rings.
having said all that there is a scavance piece of the pump ultimately at the other end of that S hose, it must be designed in such a way that the oil does in fact not flow back, so maybe this check valve is just a mitigation to a failing oil pump ??
either way i like discussing this stuff. Its just cool to understand how it all works.
my understanding of this is a little bit different.. I dont have a 3.2 so forgive me if i speak incorrectly.
Whether you have a valve or no valve, the oil in the head will leak past the worn valve guides and down into the combustion chamber, that area should never be devoid of oil no mater what, so even if you have a check valve in there the hot oil in that head is going to start to run down as soon as you shut off the engine, obviously overnight more will run down so blue smoke in the morning.
I thought that main function of the valve was to prevent hydrolocking of the engine, and blue smoke caused by excessive oil in the crankcase seeping by the rings due to the horizontal low placement of the cylinders. over extended period if enough leaked back i would imagine a lot of oil would sep by the rings and in storage could fill it up , being very bad, or mid term cause blue smoke by creeping past the rings.
having said all that there is a scavance piece of the pump ultimately at the other end of that S hose, it must be designed in such a way that the oil does in fact not flow back, so maybe this check valve is just a mitigation to a failing oil pump ??
either way i like discussing this stuff. Its just cool to understand how it all works.
I think the check valve helps with the blue smoke on startup if you have worn rings or valve guides, or park at an angled slope, especially ***-down. Would not surprise me if it helps with leaks, particularly any seal that is below the level of the sump oil that may be shrinking while the car is stored. I have not heard of aircooled engines becoming hydrolocked by oil (gasoline, yes), and Rothsport does not market the valve that way. https://rothsport.com/products/oil-i...-72-89-911-930
11-01-2023, 11:34 AM
Rothsport Anti-Drainback / Check Valves on Oil Return Line
