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MG MGB Technical - k&n oil filter

Interesting....I installed a KN oil filter a few months ago on my 1800GA that has about 3,000 miles on a fresh rebuild and an upright filter adapter. Prior to the kn I used fram ph3600 filters.

With the fram, I would crank the engine for about 5-10 seconds before I'd get oil pressure, then I'd start the engine.

With the KN, it needs to crank a good minute with ign off and even then the pressure just registers. When I start it without pre-cranking, it runs several seconds before pressure registers.

I bought the KN because I was looking for a superior anti-drainback valve, but the fram seems to perform better. I'm going back to the fram asap.

Another note: While speaking to Kent Prather, I mentioned the idea of pre-cranking, which has been debunked here in the past, and he highly reccommends the practice.
Fred H

Fred, I installed a K&N last fall, with pressure coming up right after ignition. The pressures on the gauge seem the same as before when I had used avMotorcraft FL-300. I have a '72B with the still original engine with 101K miles. My only question is if the K&N is till worth 2x more than all the other readily available filters. I am a big believer in the air filters, but I haven't yet decided what my next oil filter would be for the B. I use Purolator in most of my other vehicles, never had a problem there.
Joe

It has been suggested to me that I should bleed the feed pipe to the oil gauge. If there is air in there I'm told that this can cause slow response of oil pressure needle. What do people think of this as an option, rather than drainback valves failing all the time?

Iain
I D Cameron

I can hear the difference when the pressure comes up - when running with zero registered on the gauge the engine makes horrible noises. :(

Tim.
Tim Jenner

Fred, when you replace the filter please let us know how much oil has remained in the filter when you pull it off.
I have used Fram, PH3600, on my TD and put one on my "new" mgb and have been very please with how quick the oil pressure comes up. The filter that was on my B when I purchased it was an STP S-0228 and although it may have been over six months since the car had been started the filter was still quite full.

Iain, I have been told that since air is compressible it's presence in the line to the oil pressure gauge has no affect on oil pressure readings. But, I have read accounts where the writers swear they achieve better results by bleeding the line.

Regards,
Dennis
D F Sexton

lain When I started my apprentship in the motor trade almost all cars had mechanical oil gauges and I have never heard of bleeding the line until reading the MGB threads. I would much prefer air in the gauge mech. as it is kinder to shocks and still transmits pressure the same as oil. Denis
DENIS

Fred. Many years ago, one Bob Wilson, who was, back then, a frequent contributor here, mentioned the use of the Mann W 917 oil filter. I have used both the Mann filter and the K&N filter over the years. Now, I purchase the Mann filter in bulk from my local BAP store. With the two RB cars, the oil pressure comes up almost immediately. They have rebuilt engines with new oil pumps. With my 68 GT, there is about a 2-3 second delay before the gauge begins to climb upwards. This is with an old, worn engine. This held true with both the Mann and K&N filters. When I purchase the Mann filters in bulk, they cost me less than half the amount of the K&N filters. Changing the oil and filters every three months, I have not noticed any performance differences. Thus, the problem you describe is not, in my opinion, something you can blame on the oil filter. My experience suggests that the K&N filter works perfectly well. If, however, you have better experience with another brand, use it.

As to the "bleed the oil pressure line" question, my experience mimics Denis's experience. I have never bothered to bleed an oil pressure line and have never had any problems associated with not bleeding the line. Les
Les Bengtson

I found the post that I had read referring to bleeding the gauge. It was posted by somone who often passes on good advice on a UK BBS that I read.

"An observation about bleeding the gauge. Air is compressible compared to oil so if the capillary is primarily air it won't read as quick as if it's full of oil. The thing is, does it drain back into the gallery when you switch off? If it does, then bleeding will make no difference. If it doesn't then you will only get a true picture, certainly in terms of pressure response from start up if you bleed the gauge. The factory V8 is known to have a slow needle response which I put down to draining back, and the take off was moved from the filter head to the pump to address customer fears. Having said all that I've always bled my gauge after strip down. It shows clearly that the pipe is clear."

I suspect it is one of these thing that some people follow and some don't.

Iain
I D Cameron

Bleeding the line to the gage??? what are you using 1/2" pipe? Folks, look at the size of the line...the total volume is less the the pumps capacity for 1 rev of the motor.

Fred, take off your K&N and inspect the anti backflow valve. On some filters they are better the others. also, if your engin runs on after you turn it off it may, as some do, rotate backwards as a last gasp of life. If this happens the backflow valve is permanetly damaged and you will have low oil on ever startup from then on.

I stick with the Fram or WIX on my 73B. Over the years they give less issues than the others. Also, I have kept my toy stock and the anti run-on valve does just what it says and keep it from running on backwards and messing up filters.

Cheers Doug
Doug Gordon

Use a Mann W 917 and your problems are over _ I will not buy a Fram filter for anything I own
Gil Price

Doug, it's a possibility because I do have some run-on once in awhile. I did before the kn, but maybe the frams are made a little different. I know I've never heard of that issue before this. I need to change it before I take another drive. I'll post the results here.

Thanks
Fred H

My '72 GT has a Fram filter, and shows 60-65psi straight of the bat. I was worried that the guage was faulty...

I have a Mann W917 waiting to be put on, I guess I'll soon notice if there's any differece.

I'll let you know.

Rich
Richard

This thread was discussed between 05/07/2004 and 07/07/2004

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