Idle and Start Issue

Hello everyone,

I’ll try to be as informative as possible in order to yield the best advice from everyone here on the forum. Car has beeen driving absolutely flawless for the past 1500 miles. Done a handful of trips that were 100 miles each way, trips around town, and everything in between. I was on the freeway going about 60 the other day and out of the blue developed a noticeable valve clatter. Within about 20 seconds, I lost power and the car died on an off ramp of the freeway.

I can get it to start, but it dies as soon as it does unless I get the rpms up to about 1500 (even then it idles extremely rough as if multiple cylinders are missing and there is clearly tons of lifter noise). Has a full tank of gas, all fluids are reading correct levels, and it’s for sure not a vacuum leak (all hoses are new as of June this year).

About the only thing that I can think of is the oil pump considering, if it failed, it would cause excessive valve train noise. However, my oil light never came on indicating low oil pressure (I verified that light works as well). In the past 18 months of ownership, the only mechanical things left that I haven’t touched are the rotating assembly, oil pump, camshaft, or lifters. I’m open to run some other tests that may help get to the root cause and would appreciate any input you all have.

Best, Chris

First thing I would check is the oil pressure with a mechanical gauge. Then the fuel pump by doing a volume or pressure test. Other things to look at would be fuel filter, and the wet fuel level in carb, the distributor for excessive shaft wear too. You didn't state the year or model of car or engine so If it's still a point ignistion system check the condistion of those plus the condenser and check to see if it's mounting is loose too. Good luck

my new fav: isolate it by pullin a plug wire?
compression test? just cuz sometimes it's hard to tell 1 noise frm another?

Hi, after the checks Bubba mentioned, I would pull the valve cover and see if you bent a push rod or something else went bad in the valve train.
That could explain the noise and rough running.
I assume you checked the oil and the crankcase is not full of gas. A bad fuel pump can leak fuel into the oil.
Good luck

Cday07":18nif5k3 said:

... out of the blue developed a noticeable valve clatter. Within about 20 seconds, I lost power and the car died...

(... it idles extremely rough as if multiple cylinders are missing and there is clearly tons of lifter noise)...

Click to expand...

STOP!
Do not pass go, do not collect $200. Get that valve cover off and see if the pushrods are where they belong. If not, find out why. If they are correct, you need to find out if the oil pump is still being driven. Pull the distributor and examine the drive.

I would not attempt to start this engine until I was certain that these things are correct.
Joe

I would say the same as the others, remove the valve cover and check the pushrods and operation of the valves, like they said if that’s not your problem then check the oil pump by hooking a gauge to where the sending unit plugs in and with the distributor out you’ll see a shaft, with a correct bit on the end of a drill WITH LOTS OF TAPE holding it on (you don’t wanna have to go fishing for a bit) try and operate the oil pump and see if it creates pressure at all. Hope this helps

It’s been a little bit since I was able to get under the hood and appreciate all the quick responses. It gave me some homework to do. And a couple points of clarification; one, it’s a 65 200 Mustang with a DUI ignition system and C4 auto trans. Second, there was no gas smell in the oil (it’s still a very golden brown since it’s last oil change about 500 miles ago), so we can rule that out.

I haven’t pulled the valve cover yet, but I was able to do a oil pump test by hooking the oil pump shaft into a drill and going clockwise with it (same rotation as the motor) while having a gauge hooked up to the sending unit port and it peaks around 13 psi (the drill I hooked it up to has a top speed of 1600 rpms). Have not tested the fuel system yet since I haven’t attempted to turn the car over since rolling it into the garage. Will be pulling the valve cover in the next couple days to get some eyes on the rocker arms and push rods. I will report back then. Thanks for all the input!

I was forgot to mention the oil pump shaft. Neither end has any signs of the shaft rounding off or other wear. Both ends appear to be in good working order.

Cday07":2dnqw0bx said:

...peaks around 13 psi (the drill I hooked it up to has a top speed of 1600 rpms)...

Click to expand...

Hmmm... the oil pump turns at the same speed as the distributor, which turns at half-speed of the crankshaft. 1600 rpm equates to 3200 crankshaft rpm; your 13 psi reading seems a bit low to me, especially with the oil not being hot.

Hi, 13psi is very low.
The drill should have had a lot of resistance.
Was the drill spinning full speed or kind of slow?
Kind of slow could explain the low pressure.
Time to pop the valve cover. You need to see if oil is getting up top.
Good luck