DeltaLou

Hello,
Has anyone dealt with hot start problems on the 455's? The car has new battery, alternator, plugs, wires, switched over to HEI. Is getting fuel and spark. Thinking problem maybe starter getting too hot because have to wait for the car to cool down to start over and even then you have to floor it and it is still hard to start but eventually kicks over. Have aftermarket Carter carb with spacer so don't think fuel is boiling. Was thinking about checking/changing battery cables to starter with thicker gauge first and then check for starter shield. Any help would be greatly appreciated. Thanks

Olds64

You can have your starter tested at the parts store. It may be on the way out. Are your battery cables in good condition? There should be no fraying or corrosion on them.

joe_padavano

Welcome.

How about you tell us what you mean by "hot start problem". Is the starter not turning, or is the engine cranking but not catching?

DeltaLou

I had a mechanic shop test the battery, alternator, starter while car was running on their handheld analyzer. They told me my alternator was going so I replaced it. I will check the battery cables next as you recommended for any fraying. Would larger gauge cables help?

DeltaLou

I would believe the starter is not turning because when it is hot I hear a "grumble" repeating several times while foot on accelerator to start. Eventually, it will start but barely. Also, had the transmission serviced with new gaskets and seals and noticed the problem after this was done. I've had the car for over 20 years and never recall having this problem.

joe_padavano

"I would believe" is not really helpful for diagnosis. Either the starter is turning or it is not. Have someone look at the fan belts while you turn the starter. If they are moving, the starter is turning. From the info you've provided so far, it is impossible to tell if this is a starter problem, a fuel problem, or an ignition problem.

Olds64

Larger battery cables can carry more current but it may not solve your problem. Next time you need to start the car hot use a rubber mallet and hit the starter a few times before turning the key. If it starts easily then that can indicate a faulty starter.

DeltaLou

Okay, will try that and see what happens.

droldsmorland

Lou as Joe states troubleshooting requires a good technical description and a certain approach to narrow down the problem(s).
A hot start problem is generally is two things.
1. Fuel-related. The engine turns over easily with the starter but sputters backfires or takes longer to fire up. Cause: Heat soak, today's gas and other things additively.
2. Electrically-related. Engine not cranking or cranking slowly. Cause: A breakdown of something in the starting system...the battery, the main cables, the connections, the starter or its solenoid etc...

If I'm deciphering your description properly I'm leaning towards the starting system by the mention of "grumbling" sound. A 50-year-old charge/start system inevitably needs all its electrical connections cleaned and sealed with ignition sealer or battery terminal protectant spray. A voltage drop test of the systems will find the weak spot. But we can start simple as should all troubleshooting.

1.Clean and inspect the main battery cables on both ends. If they are original, damaged or simply worn out consider replacements. Fusick offers the correct size and quality replacements. Don't go cheap on the cables. Exact fit cables are your friend here.
2.Load test the battery and the starter. If either fails, replace.

Grumbling to me suggests a bad starter. I'd suggest rebuilding the starter by a reputable starter rebuilder vs a big box remanufactured unit. Most OEM replacement parts and workmanship available today simply do not match 72 OEM. from a quality standpoint, for the most part. At a minimum don't turn in the OEM starter(or alternator) as a core. Hang on to it and have it rebuilt as mentioned. I highly suggest installing a truck solenoid and a mini heat shield. The truck solenoid is heavy duty and will stand up to the heat better. The heat shield will deflect the radiant heat from the exhaust. I went so far as to wrap the pipe by the starter with a special heat blanket. Problem solved.

Note: if you do go for a replacement starter be sure you get the high-torque version. There is a low torque version and both will fit, thou visually and mechanically the low torque is no match.

oldcutlass

I find the older I get the more I grumble... Before you start replacing or rebuilding do some troubleshooting. I'm with Joe, not enough real info to go on here. Perhaps a video?

rocketraider

If the trouble started after the trans R&R the starter may be slightly out of alignment. You can shim the starter to get correct clearance and most auto parts stores will have shims. Rule of thumb is 1/8" clearance between starter drive gear and flexplate ring gear. A wire coat hanger is almost perfect tool for this alignment job.

Toro X6

Don't overlook the not so obvious... These vehicles need a group 78 battery capable of delivering their rated amps.

If you have a weak (worn out), cheap (can't deliver its rated amps) or undersize (not group 78 battery) start there (pun intended).

All of those things can cause the slow-cranking-when-hot issue, if that really is what's happening on your vehicle.

matt69olds

Make sure the battery is good. Take it to a parts store to have a load test done. Rule of thumb, the battery should be able to supply 1/2 it’s CCA rated draw for 15 seconds, and the voltage not drop below 9.6 volts. For example: a battery with a 700cca rating should be able to supply 350 amps for 15 seconds, and not drop below 9.6 volts.

If if the battery test good, make sure the cables are good. Do a voltage drop test. There sre videos on YouTube that can describe the procedure better than I can. Basically, put the positive terminal of a meter on the positive post of the battery, the negitive test probe on the starter battery cable stud. While cranking the engine, you shouldn’t see more than about .3 of a volt on the meter. If so, that means too much current is being lost in excessive resistance, vables mot being being enough to carry the current (and causing the current to overheat the cable). Do the same test on the negitive cable, hopefully that will help narrow down your trouble spot

DeltaLou

Tried using a rubber mallet to the starter once engine got hot as recommended which did not help. The connections to and from the starter are clean. The battery cables are 4 gauge and the starter is not the original. When cranking engine on hot start up belts are turning. I don't know if this is related or not but the center of the intake gets extremely hot shortly after starting. I have attached a picture showing the white spot on the intake where the EGR/heat riser passages are. I hooked up a mechanical temperature gauge to monitor the engine from cold start up to hot. The meter showed slow rise to 180 then to 184 for several minutes. After that, it came back down to 180 and held there without increasing. Once engine was off the temperature increased to 193-194. I appreciate everyone's input thus far. Thanks to everyone for their input.

Olds64

Those temps aren't out of the ordinary for a coolant temp sensor. The white discoloration on your intake manifold could be due to cheap paint. Do you recall what kind of paint you used to spray the intake manifold? Since the belts are turning when hot you know the starter is engaging. Have you set the timing, idle and idle mixture screws recently? How does it run?

DeltaLou

Update so far: May need engine rebuild. When engine is hot only getting 3psi at idle. The car is at shop now for a diagnosis. Does anyone know of a good re-builder (if it comes to that) in the Phoenix-Mesa-Scottsdale) area? Dealt with one years ago on my suburban and it was a nightmare.

Olds64

You mean one of the cylinders reads 3 psi on a compression test, or the fuel pump is putting out 3 psi? Or do you mean the engine is pulling 3" of vacuum at idle?

Kennybill

"May need engine rebuild. When engine is hot only getting 3psi at idle."

Are you talking "oil pressure?"

Fun71

That is completely normal. When the engine is running, there are 1100ºF exhaust gases flowing through the crossover in the intake manifold, so that area gets very hot and the paint cooks.

droldsmorland

That's why I block off that offensive passage. Heres the manifold on my 400 that was painted 15 years ago.

Olds64

If one of your cylinders has 3 psi of compression then give us the compression test results. You may have a blown head gasket. If so, you can do a cylinder leak down test to determine how the cylinder is loosing compression:


If your fuel pump is putting out 3 psi of fuel pressure that isn't hatefully low. You could replace the fuel pump if you want.

If your engine is pulling 3" of vacuum make sure you don't have a vacuum leak. Once you fix any vacuum leaks and tune the engine you should get decent vacuum (at least 18" of vacuum).

zeeke

Wow, we are all over the map here. Might be time for a new mechanic. Slow down before you start pulling motors. How do we go from hot start issues to a complete rebuild? As Joe P. told me a few years back, "pictures would help". In this case a cold and hot video would work best. What trans work did you have, a fluid change? They shouldn't have touched the starter for that. Again slow down. Owning and repairing these cars requires patience. GM hoped these cars met the crusher within a few years so people would continue to buy new.

Koda

First, check your oil pressure with a good gauge, and I presume you mean OIL pressure is 3psi not vacuum, fuel, compression, tires, or ambient pressure.