Hello,
I did a search to find out why my choke light comes on when I brake AND my oil pressure drops to zero at the same time, I'm sure that they are inter-connected. The search yeilded a few things to look at, firstly, check the choke relay I can't do this as my 87 El Camino did not come with one. Mine does have the oil pressure sender and an oils pressure switch, I changed the sender about 2 months ago in hopes that this would cure the problem, it has not. Would the switch be causing this problem? Before I change that I wanted the informed opnion of this group as to what else might be causing this. Thanks for any help.


August

Is been a while since I looked at the schematics for that circuit but I am pretty sure that the Choke is hooked up through the Oil Pressure sending unit. I think they did that so that if the Oil Pressure didn't come up during cranking then the choke heater woldn't engage.

If your Oil pressure sending unit has two prongs then try reversing the connector (Turn it 180) and plug it back in. See of that helped. I doubt it will but its a start. As long as the choke is drawing curent (trying to heat) you will have a light. Once the heater gets fully relaxed it should quit drawing current. If it doesn't go off and your sure that the Oil pressure sending unit is working good then your could have a bad choke.

You can check the wiring by removing the choke from the circuit, the light should go off. Check it cor cracks that can short out against some part of the motor. If I remember correctly the circuit should have 12V on it while the key is in Run position. Once the Oil pressure builds up then it completes the circuit to the choke turning it on.

If I have some time and you don't get a better answer then tonight I'll look through the diagnostics in the Manual and see what it says and post that.

Good Luck.

Pete

Pete,
Thanks for the info, the light only come on when I'm braking, while I'm driving the light is off at freeway speeds my pressure reads around 30-40, at idle it's 5-10 in that area. I had taken it to the dealer a while back and he said my pressure was fine and not to worry about the light, I do worry as it(the light) was put there for a reason. Thanks for the help, I will check the 12v to see what's happening there, this is a new carb I purchased from where the dealers send there carbs to get fixed out in my neck of the woods.


August

...my choke light comes on when I brake AND my oil pressure drops to zero at the same time...
There isn't a choke relay in your Elky. The 12V for the choke coil comes from the ignition switch, goes through the oil pressure switch, and then to the choke coil.

The oil pressure sending unit has nothing to do with the choke. It's only for the oil pressure gauge. The oil pressure switch inhibits the 12V from getting to the choke coil until the engine is running. If your oil pressure is dropping, then the oil pressure switch is opening. That's probably why the choke light is coming on. The light will also come on if the choke coil is bad.

What does the oil pressure usually run at? Does the oil pressure drop when you take a sharp turn? Have you checked your oil level recently?

:mrgreen:

As long as the choke is drawing curent (trying to heat) you will have a light.

Once the heater gets fully relaxed it should quit drawing current.

You can check the wiring by removing the choke from the circuit, the light should go off.
Sorry Pete, but all three of those statements are backwards.

If the choke coil is drawing current the light will stay off. The choke coil will continue to draw current as long as the ignition is on and the oil pressure switch is closed. If you remove the wire from the choke coil the light will come on.

:mrgreen:

You guys are great! I will change out the oil pressure switch. My Oil level is fine, the light only comes on when I brake, the oil pressure does not go down when I'm making a sharp turn and my oil pressure usually runs between 30-40 sometimes I've seen it go down to 20 and in the morning when I first start it it's at 40-50. Does this sound like the switch is going bad or is bad?


August

Check the connector on the oil pressure switch before you change the switch. You may just have a loose connection.

:mrgreen:

i was thinking on this. if you are traveling at a steady speed and hit the brake pedal just enough to turn on the brake lights, does the light still come on, or do you have to brake fairly hard? Because if the light comes on only with the brake lights on you might have a bad ground at the brake light sockets. the brake lights might have to find a ground path through the park light circuits and through the instument cluster. it may sound weird but when you have 2 unrelated circuits reacting to eachother its usually a poor ground. you may even pull the cluster and check the printed circuit (where the connectors plug in) make sure the copper foil hasnt come unglued and crossed to another circuit good luck

Good point,
I have to apply a moderate amount of braking for the light to come on. With a light pedal I can prevent the light from coming on, from medium on up it will come on. I checked the connector last night, unplugged it cleaned it and replugged it in, still the same problem. Now I need to find a switch as the one I picked up only had a single connecter and the on e I need requires a double connecter(found this out late last night) had to put the old one back in. Thanks for the help, as soon as I put the new one in I will let you guys know what happened.


August

Unplug the oil pressure switch connector and put a wire jumper in it to simulate the switch being closed. Be careful it doesn't short to ground as you'll have 12V there with the ignition on. Try driving around and see if the choke light still comes on. If it does then it's not the switch.

:mrgreen:

Ernie,
Great idea, will try that at lunch time.


August

Ok,
tried bypassing the switch, replacing the switch still the same problem. I did notice when I make a 90degree turn(sharp turn) with no throttle bieng applied the oil pressure does drop about 15pounds. During freeway driving speeds my pressure is at 30 in the city it's about 20-25. Anybody have a clue why this is happening?


August

A little update to the last post, I drove around this weekend and the problem is still there no change, whenever I off the gas the oil pressure will drop, when I'm stopped at a light and idleing, it's around 5psi(looking at the guage) when I get going it will pop up to 20-30psi dending if it's freeway or city driving. I also noticed a strong smell of gas when I removed the air cleaner top, kinda like it's running rich, it is a little hard to start in the mornining but after run fine. I put in a new cap and rotor and msd 8.5mm plug wires to see if that would help, it has not.


August

August, I hesitate to say this, but at this point I would suspect you have a worn oil pump. I think your oil pressure sensor and oil pressure switch have been telling you the truth all along. :-(

:mrgreen:

That's kind of what I thoght as well, I was told it might also be a worn cam or crank, though I don't see how. I don't have any of those noises yet, If I have to go and replace the pump, I'm thinking to go ahead and replace the engine with a 350. Would the dipstick be in the correct side if I got a same year block(87) or should I not worry about that?


August

Worn crankshaft bearings will give you a similar problem to what you describe.

Well,
I guess that settles that if I have to go and replace the pump and check and possibly replace crankshaft bearings I might as well replace the whole engine with a 350. In regards to my engine(1987) does it matter what year the block is? I have to be able to put all my smog stuff on the block. I would like the dipstick to be on the same side as I have now(passenger side) do you know what year block would allow this? Thanks for the help.

August

In regards to my engine(1987) does it matter what year the block is?
Your 87 305 motor has a Vortec style intake so you'll need a 87 and up long block.

The ZZ4 has a passenger side dipstick and will accept your intake too. (hint,hint) :wink:

:mrgreen:

Ernie,
I actually like to build engines, so I will find a block and go from there, I should be able to use my intake with the 350 should'nt I? It's a Performer plus with egr port smog legal, that would one less thing to buy. The ZZ4 is nice but the price hurts, I can build a nice motor for that much. :-D


August

none of my business, but chevrolet didn't start the quote vortec intake with 8 bolts until 96. just did a manifold swap on a 94 and it still had 12 bolts.

Sorry, my mistake. :oops:

:mrgreen:

Yes,
New heads are in order, now which ones.... maybe the vortec heads would be a good fit? What other ideas on heads, going to go with the comp cams 268he as its the largest they have that's smog legal.

August

if you go with the vortec heads be prepared to buy a new intake manifold, center bolt valve covers, a whole new system for plug wire looms. also the later model blocks have no place for a mechanical fuel pump.

Greasy,
If that's the case would it be better to go with another type of head, or go the complete vortec swap? To all, with the above statement how about some head recommendations.

that is a question only you can answer. i'm in the process of the complete late model block, vortec heads, and 700r4 tranny swap. what i thought would take a month at the most is turning into 3 months. granted i don't get to work on it all the time due to business {self employed} but i really didn't check into everything involved before i started. forewarned is forearmed. just thought i would pass that on. also if you have or are intending on the tranny upgrade, i will mention that unless you already have an od tranny, tv cable linkage is completely different than kickdown linkage. then to complicate it even more, throw in the vortec setup. i looked at a lot of "universal" bracketry and even bought some only to have to return it. ended up fabbin my own out of some stockers. don't know yet how well i did. heard that edelbrock makes a bracket for tv linkage, carb linkage, etc. specifically fot vortec heads. nobody in this area has one or even seen one. got a pn here somewhere but going to try my homemade setup first. good luck. normally i believe in the KISS method. KEEP IT SIMPLE STUPID. best of luck with whatever you decide and if there is anything i can do to help just holler. anybody have a cowl induction hood they want to get rid of? told you i didn't think it all through. lol

Thanks for the info and the heads up, I like to plan ahead whenever possible to try to avoid any problems that I can, I just had my tranny rebuilt so I will be using it, my new enging will be a mild build so to be able to pass smog here looking for around 300-350hp max any more and I might start running into problems.


August

Lokar makes a TV cable for the 700R4 and throttle TV bracket for their throttle cables and TV cables. The 700R4 has to have a pressure adjust done before you drive it to make sure it shifts correctly and Bowtie Overdrives has the procedure in detail on their web site.

The newer blocks can be machined to use a mechanical fuel pump and would have the dipstick on the pass. side of the engine. Also new blocks will use Roller Lifters naturally so they are better. Vortec heads can handle putting out up to 400 Hp without changing the springs. If you really want to get simple find a serpentine setup off a newer car or truck at a Junk yard. Water pump and all. I think, not really sure but I think that the Vortec setups use a reverse flow water pump.

Just a thought.

the serpentine belt drive is what requires the reverse rotation water pump from what i have been told. got one here off a 94 pu and it is easier to adapt than an 88. all the accessories are on aluminum brackets that bolt to the front of the engine. thought about it for my 86. maybe next time. lol.