hey forum! new to forum and recently purchased my first cadi. i picked up an 87 fleetwood with the 4.1 L with 124k. i'm having a few issues with it that i hope are fixable because i really love this car! backstory- one owner car, regularly mantained, appears to have been babied, garaged, beatiful car. ok so the problems 1. low oil press indicator flickers\is not steady\ at idle in park,this only happens after warm up. 2. idled for about an hour and the coolant temp fan came on 3. downshifts real hard, shifts up not so hard.
what ive done; through posts on this forum i learned about the diagnostics and checked for error codes-no error codes. verified that the fans do work with the diagnostic. coolant looks new as well as cap. oil level is good and is not due for another change for about 2k
what i will do; pray i didnt get one of the "cursed" 4.1 motors, and i plan on doimg a complete tune up, plugs cap filters. look for possible worn motor\tranny mounts and check cv joints for hard shift. being as the coolant looks brand new should i flush to be safe or just go ahead with the sealant tabs?
thanks in advance for any help

With 126K, you likely don't have a 'cursed' 4100. It would have gone bad long ago.

A flickering oil light can have many causes: weak or clogged oil pump, erratic oil pressure switch, sludge in the return galleys, etc. I'd suspect the latter due to the miles. Oil builds up in the upper channels and inside the valve covers, and just trickles back into the pan. Not sure what the cure is, other than a good high detergent oil to break it down, and a couple of short interval changes. First though, try disconnecting the oil pressure switch (the switch is near the oil filter) and cleaning the contacts. If that doesn't work, find a shop that will do an actual oil pressure test for you.

The coolant light is interesting, in that it took an hour of idling for it to come on. Are you sure both fans are operating? Is the coolant level up to the neck of the rad? You might have a plugged core in the rad also.

You say the coolant looks new - does that mean it looks green and clear? If so, that means the sealant tabs have not been used. It should look like really dirty dishwater. It's cheap insurance to just drain it, flush with distilled water, drain again, refill with fresh 50/50 and put in the sealant tabs.

The hard downshift is almost certainly the vacuum modulator on the trans. If you look down between the firewall and the engine on the passenger side, you can see it. Relatively easy fix.

Good or bad oil pump, i'd throw in a gerotor 4.9 oil pump with a 4.9 oil pan, much more effecient. Go buy some autometer 2 5/8" gauges, oil pressure, water temp, and a Volt gauge. Not electric gauges, mechanical is the best. Do not run any type of engine cleaner, replace the oil pump and pan to a 4.9, and drive. I did this on my 87 deville and the engine stopped making noises, oil pressure is about 3 PSI higher than old pump. If you hear a low moaning sound upon cold start up, your oil pump needs to be replaced no questions asked, it is the oil pick up vibrating, this will cause oil to foam up a lil' as it stirs it up. This was stated in the recalls for the 4.1.

thanks for the quick reply noah. i made a mistake in my post. i meant to say that the oil light flickers when at idle in gear, if i put in park and the idle is a bit higher it doesnt flicker nearly as much. also if i just rest my foot on the gas while in gear it goes away. the cap and rotor are worn out and i have yet to replace the plugs so could it be possible that weak spark is causing low idle and therefore low oil pressure? regardless, i did try cleaning the contacts on the pressure switch with no results. i went ahead and changed the oil with a full synthetic 10-30 as well as an oil additive. i thought about getting a gauge cluster(oil press,water temp,alt) instead of relying on the dummy lights but i think i read somewhere ih the forum that oil pressure was at stock only 8psi in idle, would that even register on a gauge like that? as far as the flush goes drain old then fill the radiator with the distilled water and then run it for a while to flush? i checked the half shaft and there is alot of play in it on the drivers side and if i drive with the window down i can hear that it is obviously shot, possibly due to the vacuum modulator.

is the 4.9 gear all straight bolt on? what other upgrades are there for the 4.1?

Normal idle oil pressure for the 4.1 is 12 psi. The light won't come on until the switch senses pressure below 4 psi. Again, I'd get the real oil pressure tested so you know where you stand first. In some cities, Advance Auto Parts will do this test for little or no charge.

You can put in a gauge cluster if you like, but realize that every component of these cars is interconnected through the ECM and BCM computers. When you start removing electronic sensors and replacing them with mechanical, the computer inteprets this lack of input as failures and sends up the appropriate warnings. I'm not even sure you can replace the oil pressure switch because it's tied into the fuel pump circuit.

You are correct on the coolant flush procedure. Be sure to let it cool at least an hour after running with the distilled water. NEVER remove the cap even while the hoses are warm.

You can check your idle rpm and coolant temp through the OBD. Enter diagnostics and run the codes. When the display reads .7.0 , press LO until display switches to E.9.0 . Press HI to step through the ECM data cycle, identified by the display P.x.x (where P means parameter, and x.x are step numbers). Each HI press advances the parameter sequence. P.0.4 is coolant temp (in celcius), P.1.1 is engine RPM (multiply number shown by 10).

The axle shaft play is a matter of concern. That alone could cause a clunky downshift if there's enough slack in the CV joint.

12 PSI is @ 800 rpms, my oil pressure is about 5-6 PSI at idle warmed up @400-450 rpms, the 4.9 oil pan and pump are direct bolt on. The drive shaft for the oil pump needs to be cut a little bit. I took out the oil pressure sensor and installed an autometer mechanical gauge. Nothing has changed. But for water temp, i spliced a heater hose just above the vaccuum resivoir and put a T fitting in, do not remove the factory water tempurature sensor.

thanks for the info guys. to noah- gool call on the vacuum modulator. i think the car sat for a while maybe up to a year so things have gotten sticky or stuck, like the vacuum modulator. i pushed up on the diaphram of the modulator a couple of times which apparently freed it up because walla no more hard shifting! check one off the list.
to caddeville- do you need to buy the pan? is it obvious that the oil pump shaft needs to be shaved down, like it bottoms out or something so its clear where and how much to cut down?when oredering the pan\pump what make model year or did the fleetwood have a 4.9 option?

any year (1991-1995) 4.9 on any cadillac, 4.9 only available on FWD (yours is). The 4.9 pump is a completly different design from the 4.1/4.5 pump. The 4.1/4.5 pump is a spur gear type, just two gears inside rotating opposite directions. The 4.9 pump is a gerotor type, which is muhc more than just gears. The 4.9 oil pump will not work with the 4.1 oil pan as the pick up tube sits much lower than the 4.1 tube and will hit the oil pan; thus the oil pan will NOT come close to the block to bolt up. The 4.9 oil pan also has a baffle inside to ecorporate the pick up tube. The shaft needs to be cut I THINK about half an inch, but you would just have to measure the distance beween the pump and the block (wheres the bolts go in, thats how i did it). I will take pictures for you of the old oil pump, and the new 4.9 pump when i go to change the oil pan next week.

Don't go to all the trouble of changing the oil pump until you're sure yours is bad. Higher oil pressure doesn't always mean 'better.'

i figured out the high water temp tonight. it seems that if when the key is in the ignition and there is slight pressure backwards on it while running the light comes on. i can now rest easy on two of my three problems, water temp is ok and fixed the hard shift. the oil pressure is going to take a little while at least untill i can get an accurate oil pressure taken. once again thanks to noahsdad and caddeville for your advice it really helped out alot. i will post again when i get the accurate oil pressure.