Irratic idle on my 6.2L 84' suburban
 

Hello all.
Thanks again for everybody's help a couple of years ago.
The motor swap went great and she has seen many miles.
As of late she has been surging up and down at idle.
I advanced the idle screw and she no longer stalls, although could probably get her to if I really tried.
Any help would be appreciated.
Thanks in advance,
Skye:s:

Replace the fuel return line at the frt of the IP with clear diesel rated line,then with the truck safely parked and idling,watch for bubbles in the line.

Bubbles indicate air in the fuel and that can cause your symptoms.

Often the air gets in somewhere between the fuel level in the tank and the LP.
rotten lines,pin holes in the sending unit ect.

Thanks Racer55,
I am heading out now to check for air in me fuel lines.
I will update later today.

---AutoMerged DoublePost---

I ended up replacing the fuel line from Filter to IP.
Problem solved, Thanks Racer55
SKYE

I would have expected a leak from that line-did you have air in the fuel?

Is the lift pump working?

Well, bad news.
My crankcase is full of coolant and my oil is splling out of my dipstick. She never over heated and always ran strong, always kept full of fluids. In fact just got my oil changed a couple of months ago.
Oh well.
Such is life.
I am curious if it is a cracked block or just a blown head gasket?
Guess I might be rebuilding the last motor I pulled out that has a suspected blown head gasket.
Either way I would love to get a turbo for it, NOT "BANKS" unless it is used and inexpensive. Oh...suburban will not turn over after the event.
So it goes......
I was 5 miles from home going on a 10 day road trip in Northern CA. ( 12 days ago)
There was a loud clank noise from the motor and then a low whining sound and then what sounded like grinding metal. Then the driver tail pipe started billowing heavy white smoke. Pulled over and she wouldn't turn over at all, just a "CHUNK!" sound.
Is it worth shopping for a 6.5L?

6.2 or 6.5 will both suit your needs,6.2's are/were more plentiful.

If you do get a 6.5 you will be better equipped since it most likely will already have the turbo and manifolds.

Better build for you would be a 6.2 lower end, with 6.5 turbo heads/upper parts that is the configuration Bill Heath & many run, and parts are plentiful, since you have (2) engines, take best parts from the 2 and make one bad ass engine. Bill Heath could give you some excellent advise search web for Heath Diesel

well....I had my block checked and heads done up.
Ordering a kit and rebuilding hopefully by the end of this week.
Can't seem to find a 6.5L anything let a lone a used turbo.
Might have to go with what I got and keep looking. I believe the mod in getting a turbo on my rig would be 6.5L head on the turbo side and the turbo, along with a turbo fuel injector.?
She is my daily driver and I miss her so.

just look for turbo manifolds,crossover pipe,downpipe and an ATT turbo

You can't mix and match heads. You have to use both the same. I'd say your old motor probably cracked the block/crank.
6.5 Turbo parts are abundant. You are not looking in the right places. check out the classifieds section at diesel place. Tons of 6.5 turbo stuff.
You can use 6.2 heads but 6.5 heads make it easier. Also 6.5 heads have turbo precups but that is not that big of a deal, more important that what ever precups you use, they all match.