Needs help with my '85 p30 454...it will not start hot

[Shasta]

Hi folks, I just bought my first RV in April, his name is Paul (to honor the late prior owner). my Paul is an A class Itasca, Chevy p30 7.4L with 22K (original miles). I'm still working on just going through all the systems. Engine wise, I rebuilt the carb & had a pro bore it out so the California ethanol wouldn't hurt Paul. New sparks & wires, all fluids & filters changed, & that was when he was running/starting cold & hot just fine. He started getting hard to start so I got a new (1000cca) battery & starter solenoid, the starter motor is fine... all the battery cables are in great shape, I get a full 12+ volts to the starter from the battery and the ignition. After the new battery & solenoid it started up better cold, but still is just nothing if the engine is warm. Before the new solenoid the engine would rotate really slowly and not turn over until quite a few tries. Now it starts cold with a long delay of just nothing then a big rev when it turns over. But nothing at all if engine is warm. I have run out of possibilities... any sugestions are very welcome

Thanks!  

[Jimco_W001]

I would check the engine timing.If its advanced it will start when cold but not when warm.This can be caused by to much base timing,a stuck mechanical advance unit,or a stuck vacuum advance unit.

[Shasta]

thanks Jimco! 

[0l9c7nlsuup1p]

This is really gonna be off the wall. 

I have an '85 P30 454  - actually approximately the same miles on the engine and doing the same thing - re-baselining everything for extended touring.

Engines need to breathe... first off, back in the early eighties there were vapor lock issues - probably not what's plaguing you, but keep that in mind.  They had a fix by '84 and '85, and most coaches were either retrofitted or came from factory ready to go.

Obviously, it sounds like there is something binding somwhere...

So if it was running fine and you put some new parts - now "Paul" is misbehaving because of new parts... You have to look at the new parts, and did they completely address the issue - New solenoid, old starter still doesn't crank.

When solenoids are dying, the go "click,click,click" when you turn the key, then you try jumping the main posts on the starter to see if it engages...(careful if you are not sure what I'm talking about DO NOT DO THIS- lots of juice)...if starter engages, then new solenoid, else new starter and solenoid. 

Your starter just may be giving up - just throwing more juice at it is not the answer, you'll just create more problems.... and end up getting stuck somewhere that's not convenient.  It should spin over easy hot or cold...

Check if starter/solenoid binding when hot - not just 12 volts but not seated perfectly... and, in today's world, new automotive parts are not perfect - you may have been given a flawed solenoid - or they put in on the starter wrong and it's binding. 

Check that  PCV and all crankcase breathers are new, clear, etc. - check the "check" valves...  You may have too much pressure in the engine when hot - like I said - off the wall...

Lastly - This may be impossible to try - it would be with my coach...

Can you turn the engine manually when it is hot?  It should turn over with just a normal amount of effort.  That will rule out engine issues and confirm you're on the right track with solenoid/starter issues.

Good luck

 

 

 

 

[Richard W. Cobbs]

Hi, Can you further explain this part?  

Before the new solenoid the engine would rotate really slowly and not turn over until quite a few tries. Now it starts cold with a long delay of just nothing then a big rev when it turns over. But nothing at all if engine is warm.

A long delay of just nothing?  Do you mean the engine is not being turned by the starter?  Or, the starter is turning it over slowly and then it turns faster and then it starts?

 

[Shasta]

To Angel, it did go "click, click, click" before the new solenoid. 

To Richard, yes, at this point, holding the key 'on' it does nothing, no dash lights come on, no clicking, whining, turning or anything for a long time... 10~20 seconds (feels like way tooooo long), then it finally fires right up powerfully. Since I have had Paul the engine revs high upon starting, it will slow to normal if i put it in gear or let it idle for a wile in park & tap the gas. 

When I've tried to start the engine warm (only driving 5-10min) then the engine will do that super slow rotation but not actually turn over. But that was before the new solenoid, now when I've tried to start it hot there is just dead nothing.

Also, maybe related, I am pretty sure I just got a crack in my exhaust manifold as well. its a pretty loud metal clack/ knocking noise, which is always in sync with the engine rpms, if I drive 30+ minutes it has gone away (maybe engine has gotten hot enough to expand & re close the crack?)  

thanks for all the helpful replies, its really a pleasure to find great rv peeps :)

[0l9c7nlsuup1p]

Hey,

The initial high revs is your choke at work - give the engine time to warm up before using

Manifold cracks/leaks were common with that engine - but confirm that your clack is exactly that - a manifold leak - and not lifters or worse rods (unlikely unless engine ran w/o oil) - if you can locate the crack in your manifold - sometimes they can be repaired with JB Weld.

I keep coming back to solenoid and starter... it just sounds like a bad starter  - when hot doesn't like to work... Your new solenoid is just extending the life of the starter a little. 

And you are right holding key "on" for 15-20 seconds is too long and should not be done - other things are cooking when holding it on.... (ignition circuit related)...

You can pull your starter off and get it tested at many of the auto parts places... a pain - I know - but necessary.

Disclaimer - I am not a pro wrench - but everything here is what I would do... Troubleshooting temperamental electricals on an old coach that has had any number of gorillas working on it is a challenge but there are only so many things it can be...

Question - most of the time one replaces the starter and solenoid at the same time - was there a particular reason you decided to keep the starter?

[Richard W. Cobbs]

I think Angel is on the right track.  Pull the starter and have it checked.  While it is out check the flywheel for missing or damaged teeth and tightness (no wobble) .  On re-install, replace the pilot bushing.

Good Luck,

RWC

[Matthew Tritt]

I agree. Holding the key in the start position with nothing happening is a good way to burn out the switch, but forgive my ignorance about GM equipment: is there a starter relay in these vehicles like there is on Dodges? These relays are a common source of mysterious starting problems in older Dodge motorhomes, and the symptoms sound very similar.

Matt

[Ron Gunn]

If sure the starter is good, check the ground wire, it should be bolted to the engine block (unpainted connection) not the frame.

 

[Sam Green]

Here is a link to a forum topic that I found that may be of some help to you.

http://www.pirate4x4.com/forum/archive/index.php/t-532345.html 

I hope it will help you.

[Richard W. Cobbs]

SOOOO?  What did you find out?  We are all waiting to expand our knowledge.

RWC

[Jim and Suzan]

remote starter solenoid instructions www.maliburacing.com/ starter_solenoid. jim and suzan