!972 GS Stage 1 with gauge cluster. The gauge had been working fine then suddenly screwed up. While accelerating, the oil pressure needle moves backwards (moves down to lower pressure instead of up to higher pressure). At idle it reads 1/4 and then moves downward with acceleration. Changed the sender (80psi), changed out the cluster, checked and cleaned all the grounds, checked the wire for continuity, and it still does the same thing. Anyone seen this same condition? About at my wits end now. Thanks much, Terry
...and you sure it is not working accurately? Perhaps you have an oil pressure issue it is trying to indicate to you?
How accurate could L------l------H be? Exactly how much oil pressure is two hash marks before the middle line?
It can be very accurate, it tells you what is happening. If you like numbers for reference, tee in a manual guage and plot the points on the guage, make a little chart and put in the glove box. Then you know if the 1st mark is 10, middle is 35 etc for reference. The electric guage is likely showing that you have a problem like low oil level or slosh or maybe even excessive main bearing clearance. I would start with a filter change and go from there. Anyway, the wrong sending unit won't make it read "backward" on acceleration.
I've never trusted a factory gauge. I want to see numbers. On my old 442 I had, I rotated all the Auto meter gauges so they all pointed straight up when I was cruising. Everyone always asked me why my gauges were crooked when they looked in the car:laugh: I agree though that Terry's issue may more than likely be an oil pressure issue rather than a gauge problem.
Yeah, I'm with you on that as well. It makes you wonder why the factory would make a perfectly good guage and not put numbers on it. I guess the average driver would not care. It is really just an indicator to tell you whether it is in normal range or not.
They are accurate in the sense that each hash mark represents a certain amount every time. Half way is 40, all the way up is 80. I have a gauge under the hood I verify it against. its about spot on once you learn it. its not like halfway is 50 one day and 10 the next.
80 lb sending units were used on 455s till mid Dec.'69. After that and till the end of '72 60 lb sending units were same. 350 cars used the 60 lb unit all along. http://www.v8buick.com/showthread.p...sure-sending-unit&highlight=oilo+sending+unit Comment #5.
Thank you folks - good info. Will get a NAPA OP-6637 today, plus install an electric gauge under the hood. The underhood gauge will give the real pressure. I'll update the thread with the results. I still think it's an electrical issue. Thanks much, Terry
UPDATE: I installed a mechanical oil pressure gauge (VDO 0-100psi) under the hood. Oil pressure is 50psi at idle and 80psi at 5,000 rpm (modified pump). This certainly gives me peace of mind that the oil pressure is OK. Haven't been able to find an OP-6637 sender yet. NAPA says they are discontinued. I would still like to find a 60psi sender to see if the stock gauge will read correctly. Anyone have a 60psi sender? Thanks again for the help, Terry
According to rockauto.com, the Niehoff DR135X switch fits the 70-72 GS. They don't have a picture of it, and they only have 1 left at 18.30 Then there is this one for a 69 Chevelle, http://www.ss396.com/chevelle/GAC-310.html
Thanks Larry, After NAPA told me the Echlin OP-6637 was discontinued, I went to NAPA Online and the sender came up. I clicked "Order Online" and filled out the order, and paid for it ($10.69). Got an email confirming the order and saying the sender will be shipped to me. Should know in a few days and will update should anyone else be looking for this unit. Terry
I tried to order one on line and got a message to check with my local NAPA. I stopped at NAPA yesterday and was told it is no longer available. Can anyone help me get one? Thanks in advance, UticaGeoff
http://www.napaonline.com/Catalog/R...Ntk=Keyword&Nty=1&Dn=0&D=OP6637&Dk=1&Dp=3&N=0 Appears you can order online and it will be sent to your local NAPA. Luck.
When I click on the link it says "Call store for availabilty" As I said, my local store said it is not available. Thanks for trying, UticaGeoff
Try this link for an interchange for the switch- http:/www.yoyoparts.com/oem/12630165/echlin-op6637.html
After ordering the sending unit online at NAPA and paying for it, I received the following email: Thank you for shopping on NAPAonline.com. We apologize for the delay in contacting you about your order. Unfortunately, the part you ordered is not available at this time. They are on factory back-order, and we do not have an estimated delivery date. Your order has been cancelled, and you will not be charged for the item. So much for that NAPA order! Terry
