Alfa Romeo Forums banner

61 - 80 of 88 Posts

·
Registered
Joined
·
9,977 Posts
Discussion Starter #61
Sounds perfect. The off idle pressure gauge readings are almost dead on with actual. At idle they'll read about 5 psi higher than actual. See the guide I wrote for the "normal" factory oil pressure spec at idle and off idle.

Mine reads Cold 55 idle, 70 at 3000 rpm. Hot 20 idle, 55 at 3000 rpm.
 

·
Registered
Joined
·
352 Posts
Sounds perfect. The off idle pressure gauge readings are almost dead on with actual. At idle they'll read about 5 psi higher than actual. See the guide I wrote for the "normal" factory oil pressure spec at idle and off idle.

Mine reads Cold 55 idle, 70 at 3000 rpm. Hot 20 idle, 55 at 3000 rpm.
So my range seems a bit tighter than that, but maybe thats a variation between the Sunpro sender and the Bosch sender. Either that or my engine is a bit more worn than yours and can't get the pressure as high.
 

·
Premium Member
Joined
·
16,072 Posts
I get the same readings as you, John, except I get about 25 at hot idle, this with 190k miles on the car. Mobil1 15W50.
 

·
Registered
Joined
·
352 Posts

·
Premium Member
Joined
·
16,072 Posts
If you assumed the gauge was linear, it would be about 27.5 but since we don't know (and I doubt), I can only say that in my 164s, it reads about at that mark or a needle width less, as confirmed by a mechanical gauge, ~25 psi. Of course, how accurate is the mechanical gauge? Don't know. It's all close enough, I think.

Also, the values do seem to drop ~3-4 psi if the drive is over several hours of constant highway speed as compared to a short 1/2 hour sprint, even if the engine is hot in that short drive. I attribute this to long term heat soak of all the components, and thus the oil.
 

·
Registered
Joined
·
352 Posts
Ok I just wanted to make sure it was doing something right because it just seems to be such a short range for it to move, and it never gets over 55 even cold, although I haven't really run it over 3000 rpm dead cold, but its hard to do since every time I've driven the car its been over 90 degrees ambient outside anyway. The needle in mine never really gets to 55 completely, nor does it get nearly low enough to touch that first thick line, so its a real short sweep.
 

·
Registered
Joined
·
545 Posts
The "original" Alfa gauges are crap.
I replaced the second "originale"Alfa type oil pressure sending unit in my 1991 164L last year (June 2017) at around 78,000 miles with one from Jeggs and I've been happy with it, and accept that the readings are relative, not exact.
Although the "originale" was still working, I got tired of having to clean up all the oil blowing out of the "small" hole I had drilled in the top in accordance with one of the recommendations on here. There was as much oil blowing out of that "small" hole as from a leaking head gasket, but now none, my engine is clean and completely "oil leak free."
So I will never do the "drill a small hole in the top" fix again, since I can just buy a new sender from Jeggs, with the adapter kit they also sell for NPT threads, and can remove and install the sending unit with any normal metric wrench, not one you have to mill down to fit between the sending unit and heads.
 

·
Premium Member
Joined
·
16,072 Posts
Of course, the drill the hole method works only if the leak inside the canister is very slow, as is with most of them it seems, evidenced by the gauge slowly dying over time, not failing right away. If the seal is toast and oil leakage is large, of course toss it. I have several which do work, and I installed a screw in the drilled hole in order to prevent further external leaking. Saves money if it works. That's all. No biggie.

How much is the Jeggs unit as compared to the OEM or the Sunpro/Bosch? I think I paid slightly less than $20 for the last Bosch.

Never had a problem with removing or tightening the OEM units, as it seems my 1960's editions of the Craftsman wrenches are thinner than the newer ones, lol. Just a pain to get to otherwise, as compared to the oh so easy 24V engine location.
 

·
Registered
Joined
·
352 Posts
Yeah I used the open side of a gear wrench to get mine off, just happened to be what I had nearby, I don't know them to be any thinner than other wrenches.
 

·
Premium Member
Joined
·
16,072 Posts
My suspicion has been that there is a special socket which can be used to remove and install the OEM sender, the canister having that vertical groove in the side. I thought about making one on the lathe, but never got to it. Still might if I remember, should be easy. A piece of aluminum round stock worked to shape will work.
 

·
Registered
Joined
·
1,513 Posts
Of course, the drill the hole method works only if the leak inside the canister is very slow, as is with most of them it seems, evidenced by the gauge slowly dying over time, not failing right away. If the seal is toast and oil leakage is large, of course toss it. I have several which do work, and I installed a screw in the drilled hole in order to prevent further external leaking. Saves money if it works. That's all. No biggie.

How much is the Jeggs unit as compared to the OEM or the Sunpro/Bosch? I think I paid slightly less than $20 for the last Bosch.

Never had a problem with removing or tightening the OEM units, as it seems my 1960's editions of the Craftsman wrenches are thinner than the newer ones, lol. Just a pain to get to otherwise, as compared to the oh so easy 24V engine location.
Del, what's the drilling hole method to oil sender resurrection?
 

·
Registered
Joined
·
9,977 Posts
Discussion Starter #73 (Edited)
It's in the guide. You need a rather long drill to do it in-situ . . . and it's going to eventually leak oil as the can fills up. Best just to replace it with a Bosch unit and resistor to make the gauge reading accurate. My replacement unit with the resistor has been working flawlessly for 7 years now.
 

·
Premium Member
Joined
·
16,072 Posts
Right. I dreamed up that drill the hole fix back when we didn't know about the Sunpro/Bosch unit. Just change the darn thing, although if you had to keep using the old drilled unit for some reason, I just put a sheet metal screw in the drilled hole once I drained the oil out, after removing it from the engine of course. As John says, eventually, after thousands of additional miles I spect it would refill with oil, and you would have to redrain it, OR, replace it with the SunPro/ Bosch unit.
 

·
Registered
Joined
·
1,513 Posts
It's in the guide.
What guide? If you mean the sticky, then it just links back to this thread.


Right. I dreamed up that drill the hole fix back when we didn't know about the Sunpro/Bosch unit. Just change the darn thing, although if you had to keep using the old drilled unit for some reason, I just put a sheet metal screw in the drilled hole once I drained the oil out, after removing it from the engine of course. As John says, eventually, after thousands of additional miles I spect it would refill with oil, and you would have to redrain it, OR, replace it with the SunPro/ Bosch unit.
Still curious about what the drilling is all about; I assume the bad sender fills up with oil so I drill and drain it and then slap a sheet metal screw to plug it and it works again? Anymore to it? Any link to it?

Also, it seems the thread on the block is M10 x 1.0 and Bosch sender is 1/8 NPT. Now I've read about how others have loosely screwed the sender into the block directly but Bosch makes an adapter kit (Bosch FST 7573) which has several adapters including the needed M10 x 1.0 to 1/8 NPT. Is anyone using this? Seems like it's worth the $12 for peace of mind in damaging the threads in the block. Just want to confirm the sizes and clearance for the adapter before purchase....

Thanks for the help....
 

·
Premium Member
Joined
·
27,158 Posts
What guide? If you mean the sticky, then it just links back to this thread.




Still curious about what the drilling is all about; I assume the bad sender fills up with oil so I drill and drain it and then slap a sheet metal screw to plug it and it works again? Anymore to it? Any link to it?

Also, it seems the thread on the block is M10 x 1.0 and Bosch sender is 1/8 NPT. Now I've read about how others have loosely screwed the sender into the block directly but Bosch makes an adapter kit (Bosch FST 7573) which has several adapters including the needed M10 x 1.0 to 1/8 NPT. Is anyone using this? Seems like it's worth the $12 for peace of mind in damaging the threads in the block. Just want to confirm the sizes and clearance for the adapter before purchase....

Thanks for the help....
I used correct adapter fitting from kit with correct threads but you need a good sealing washer under it. I don't think the sealing washer comes with kit. You can try to reuse one from your old Alfa sender but a new soft copper one is better to use.
 

·
Premium Member
Joined
·
16,072 Posts
No, that's it. Just remove, drill, drain oil, plug hole with screw, reinstall. Mine have always then worked again, and I imagine that since the leaky internal seal was not replaced, it will slowly exhibit the same slow failure again as the unit fills again with incompressible oil over time.

However, if you remove it, just buy the Bosch/Sunpro unit, wire in a 22 ohm resister in the line, and install. One note about the Bosch unit, use a couple of ignition or small wrenches to tighten the nut holding the wire on while keeping the inner stud from turning. If that turns you can wreck the unit since there is a wire attached inside which could be broken loose from the stud.

The first time I installed a Sunpro unit, I just carefully screwed it into the 24V head a little without the adapter kit, since the threads are really pretty close (the kit comes with the unit). Worked fine with no leaks sans washer. Later, I reinstalled it using the adapter kit w/washer, as it extended the unit a little more toward the front of the LS nose, easier to see and wire up. AFAICT, both ways work if you are careful. However, you should probably install it with the kit, thus avoiding frowns from purists, lol.
 

·
Premium Member
Joined
·
27,158 Posts
Del said,"However, you should probably install it with the kit, thus avoiding frowns from purists, lol."

Let me tell you it is no real problem to install tapered threads on Bosch Sunpro sender into straight metric threads in 164 12v block if you have a thin 14mm open end wrench. , However, installing the correct threaded adapter with copper washer under it first into engine block between the heads with correct sized socket and then installing sender into adapter is so much easier to get 14mm wrench on hex head boss of sender unit.
 

·
Registered
Joined
·
1,453 Posts
So, is the 7577 Bosch sender still as close to the Holy Grail as we can get?
 

·
Premium Member
Joined
·
14,298 Posts
I did some work to interface the Bosch sender to Alfa gauges and documented it here: oil pressure gauge
 
61 - 80 of 88 Posts
Top