Lockhart oil cooler and pressure switch

[jknappsax]

I had a Lockhart oil cooler on my 1977 GS 750 back in the day, and there was a problem when you installed the oil pressure switch in the cooler adapter; it would blink on at idle, even though all was ok with the oil pressure. Lockhart put out a mod where you placed a teflon disk under the metal plate in the switch, since the switch was now mounted horizontally in the adapter rather than vertically in the original switch housing. It didn't work too well. I had one on my 1978 GS 750 that I sold a few years ago, which I pulled off before I sold it, but forgot to take the teflon disk. I just installed it on my GS 1000, and the light comes on at idle. I also have a Reno-Bruce oil gauge, so I know the oil pressure is ok. I can try to fab up a spacer like the one Lockhart issued, but does anybody else remember this problem, or have a better solution?

[rustybronco]

Quite a few of those cooler adapters used a cap-plug looking device around the oil port. There was a thread on the same matter a while ago. I have a picture of what I'm referring to in one of my picture storage accounts. I'll post it up after I get back from lunch.

[rustybronco]

Don't have a picture of it any more but you can get and idea by looking at this picture of the adapter.



ALSO

http://thegsresources.com/_forum/showthread.php?p=977815#post977815

[jknappsax]

That's a better adapter than the one I have; I'll try to post a pic tomorrow. Mine has two brass hose-barb fittings that thread into the adapter, and the port for the pressure switch is on the side, not the top like the one in your pic. The fittings interfere with the clutch cable somewhat; I'm planning on shortening one of them to just the length of a hose clamp, and bending the hose barb a little to relieve the pressure on the cable. You don't by any chance want to sell that one, do you?

[rustybronco]

That was one I took off my '80 GS850. I don't even think I have it anymore. My '78 GS1000 came with a Lockhart oil cooler as well.

Did you look at the link I posted?

[rustybronco]

[jknappsax]

I've been looking at the thread you link to, but I'm not quite getting it. My Lockhart adapter didn't ever have a washer or seal at the end of the extension that acts as an oil pickup. The Teflon disc that they put out as a mod just dealt with the pressure switch, by removing the screw and brass disc from the end of the switch shaft, then putting the teflon washer between the shaft and the brass disc before replacing it on the switch shaft. I haven't taken the adapter plate back off to take pictures, but mine has a tube at the center reaching down into the sump like your pictured adapter does. In the link you posted, the one showing a crust washer placed on the end of this tube, is that there because a lack of internal seal causes the pressure going to the switch to go low at idle? The teflon disc was slightly larger in diameter that the brass disc; was this helping to keep the pressure to the switch from dropping? I rode my 750 on several long trips, and the oil pressure indication from the switch was never a problem. I don't ever remember having a rubber washer at the end of the pickup tube. I spend yesterday moving the clips on my carb slides, so didn't pull the adapter to take pictures. What a PITA that was!

[Nessism]

Unless the adapter extension snout seals down tight over the top of the engine oil feed port, you will get bypass leakage and the oil pressure light will flicker at low rpm, when the oil pressure is low. Not sure what the washer thing you reference is all about. I have no personal experience with the Lockhart adapter per say, but have read here several times and seen photos of a rubber hat piece of sorts which goes over that snout and seals down tight onto the oil feed port. There was someone here that found a nice aftermarket substitute part too since the original Lockhart part is no longer available.

[sedelen]

Here's mine, '79 GS1000E.


And this was sent to me compliments of Eric Bang.

[Nessism]

Not a fan of that O-ring solution because it could squirm out of place with heat and oil pressure. I've used heavy gasket paper before to make a seal, but cut it large enough (square shape) to wedge into the oil distribution cavity and not move around. I've also used an oil pan nut crush washer, and likewise trimmed it to swedge tightly into the cavity. You don't want the seal to move out of place when in use.

[rustybronco]

I'll take a picture of my lockhart adapter later on this evening as it's already off the bike.

The reason I posted pictures of my 78 GS1000E's cooler adaptor was to show you how the hoses were routed. Did you notice both lines ran between the carbs instead of around the outside like Rob's bike? If you have them routed around the outside, maybe that's the reason you're running into clearance issues with the clutch cables.

The fittings interfere with the clutch cable somewhat; I'm planning on shortening one of them to just the length of a hose clamp, and bending the hose barb a little to relieve the pressure on the cable.

[rustybronco]

My Lockhart adapter didn't ever have a washer or seal at the end of the extension that acts as an oil pickup.

It should have had one else it won't work properly.

[sedelen]

My oil lines are pretty much routed the same way, one line dropping between 3 & 4 carb and the other dropping between 2 & 3 carb, but my lines are up higher over the engine along the frame tubes as I got my oil cooler hose nipples on top of the cooler.

[jknappsax]

Rusty, mine are routed along the frame rails under the tank. The interference was because mine had brass hose barbs that were straight rather than at 135 degrees, and crossed the clutch cable. I solved it yesterday by shortening one hose barb, so it's all good. Steve, is that part with the hand-drawn part numbers 870-05 from Lockhart? Do you know if they are still available from them?

[jknappsax]

Rusty, you're absolutely right that I need that seal. I'm hoping that Sedelen can come up with a source for the part he shows with p/n 870-05. Also, I read that it's a good idea to change the oil pump gears to those from a 750, but I can't find that post. Is that the case?