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1988 454 runs loud after heating up (RV Chassis)

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New User

Jun 19, 2020, 12:22 AM

Post #1 of 5 (290 views)
1988 454 runs loud after heating up (RV Chassis) Sign In

1988 Fleetwood Southwind on Chevy P30 Chassis, 454 V8 47,000 miles
Problem: The engine makes excessive noise (sounds like high RPM) when accelerating or driving over 30MPH, but the noise does not result in power to the drive train. I don't have a tachometer, but it's probably not high RPM, but other noise that sounds similar, like an engine on high idle. Perhaps its the radiator electric fans, but the temp is not that hot (less than midpoint). The noise level in the cab makes it so you can't have a conversation.
Before the engine is warm, this does not happen. After 5-10 minutes of driving the problem starts. There is some belt squealing when accelerating at times. This carbureted vehicle has an air pump for emissions.
I suspected the transmission was the problem a while ago and had it checked out by a mechanic. They said this transmission was bullet proof and was fine. (They dropped the pan and checked it out). They drove it and didn't notice the problem that i described to them. They did solve some belt chirping issues by taking the A/C pump offline (cut the belt).

It has new batteries.
I'm a DIY-er in general, but not a mechanic. The first mechanic I hired didn't solve this, and it seems hard to find a mechanic who does carrbureted/RVs.

Any suggestions?

I plan to seek our another mechanic, but though I'd check in case the problem could be identified.


(This post was edited by lbassler on Jun 19, 2020, 12:31 AM)

Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Jun 19, 2020, 2:19 AM

Post #2 of 5 (284 views)
Re: 1988 454 runs loud after heating up (RV Chassis) Sign In

Yes this is all doable the hard part now is going to be finding the right tech who will put up with all the obstructions and size of this thing as a whole - AND have a clue what a multiple belt, carbed Chev 454 (big block) is about.

Assorted emissions still apply to these IMO do not harm how it was intended to run with adequate power for the thing.

Noise that comes on late? Bear with me still thinking of all the mess that's there to make noise:

> Exhaust things especially that "smog" pump it's loosely called is to inject air into exhaust manifolds via tubes probably that will be rusty and do and did fall out, rust out, backflow diaphragms to keep flow one way failures and more. It's quite a maze of tubes, vacuum lines and you need every one to be in place and operational!

The job is finding the right person/tech not my usual wild specifics on parts or what to fix and how. The thing probably came with and will or should work great with a well checked out Rochester Quadrajet both a fav of mine and a tech's nightmare. For you just know it's lots of detailed adjustments and diaphragms again will take some know how and parts to get to 100% again but should be able.
For now I suggest skip regular shops you need an RV place or even a marine place as the engine was a staple power plant for a ton of things so NOT OBSOLETE at all takes time the right person/people WITH THE SPACE FOR THIS THING!

Space would be my worst problem when it was new and would be now too.

Avoid the "just cut the belt" and bypass everything as a clue that isn't the right person IMO they could be fine it will just take the right person make as intended without wild alterations to what it was is fine just like anything like reckless disregard for fuel consumption for adequate power,


Ultimate Carjunky / Moderator
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Jun 20, 2020, 3:36 PM

Post #3 of 5 (257 views)
Re: 1988 454 runs loud after heating up (RV Chassis) Sign In

On a long deserted road while it is making that noise, throw the transmission into neutral. Does the noise change or go away?

Also while it is making the noise, turn the engine off. Just don't go too far to lock the column. Does the noise go away?

Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.

New User

Jun 22, 2020, 1:20 AM

Post #4 of 5 (205 views)
Re: 1988 454 runs loud after heating up (RV Chassis) Sign In

Thanks Tom and Discretesignals.
I think only a couple shops hear deal with RV's, due partly to space limitations. One made me an appointment for one month out. The tech on the phone said it sounded like a seized fan clutch.
I checked with a cold engine and the fan wouldn't turn by hand. So I have removed it and am awaiting a new clutch. I think this will solve my primary problem, then I'll be able to listen for any other sounds.
No road tests until its back together.


(This post was edited by lbassler on Jun 22, 2020, 1:21 AM)

Tom Greenleaf
Ultimate Carjunky / Moderator
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Jun 22, 2020, 2:33 AM

Post #5 of 5 (197 views)
Re: 1988 454 runs loud after heating up (RV Chassis) Sign In

Some of those in HD use (duh) really come close to locking and need to for this thing. You do want it to when hot not when colder so get a real good one with bi-metal spring senses heat to grab more or let go.

Been a while like everything some hang on too long really can feel loss of power in this thing you need also but not overheat either. Rock and hard place - no engine you aren't going anywhere, Tom

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