Got a prospect on an '86 F250 4x4, 6.9 with a transplanted ZF5. We've been around our PSDs enough, and the 300 in an old '83 F150, but no familiarity with the 6.9. What should we look for when looking at the truck?

You can do a compression test from the "outside" on this engine, right? Is it hard to do?

 

You can but you run the risk of a glow plug with a swollen tip breaking off in the head.

 

use a nut sawn in half if any glowplugs stuck
spray loosened but stuck glowplug area/threads with PB Blaster

just go to napa and tell them you need a nut that will fit the threads of the Motorcraft ZD9 glowplugs

I got nut easy at Napa but they dont have Motorcrafy ZD9's at napa so look at other parts stores if possible

Napa sells the Autolite glow-plugs which are OK but not near as good as the ZD9's

used a sawz-all with 24TPI metal cutting blade and vise to saw nut in half easily

used needle nose pliers to position each side of nut around glow-plug thread then held it with either a wrench or pliers and used a socket to keep unscrewing the glowplug

couple times I couldnt get whole nut on there so I just used one half and held it there with outside round part of wrench while loosening with ratchet

known issues for these trucks are

1) broken pick-up tubes in fuel tank(s)
symptoms are running out of fuel at half/quarter tank, surging uphill
stalling when on a grade up or down
to fix remove tanks or pickup bed, remove cover/sending units
clean tank
use a length of new rubber line to replace pickup tube and make sure it gets close to bottom of tank but not touching
cut hose at 45 degree angle opposite to floor of tank so hose cannot suction itself to tank floor

make sure you clamp hose onto sending unit

2) air leaks in rubber lines or return lines
causes no-starts, starts and stalls, surging when climbing hills, rough idle after startup
another easy fix start at fuel filter back to tank and return lines too
if fuel filter is ever NOT full of fuel when you remove it after sitting awhile you have an air leak somewhere between the fliter to the tank(s)

3) hard starting, wont in cold weather
possibly the glow-plugs and/or glow plug circuit
easy fix replace glowplugs and test relay, etc

4) wont start when at operating temp but starts easily when cold
IP is worn or dying
replace IP

5) No fuel to filter
most likely a dead lift pump or clogged filter

6) no fuel to injectors
dead IP or dead FSS solenoid in IP

7) fuel to injectors but no start
possibly clogged injectors or IP cannot produce enough pressure to open injectors

I know all this cause I've either already done it (pickup tubes, air leaks, glow-plugs) or am going through it now
(IP and/or injectors)

 

8) Oil in radiator
leaking oil/water heat exchanger

 

Also could be a blown head gasket awhtx

 

9. Coolant test for acidity, by product of combustion from head gasket or cavitation. On cold start sniff tailpipe (just like PSD) looking for coolant smell. Sure it's a PSD trick (saved me from buying a bunch of problems) but it applies here too.

Cheers,
- Jeff

 

yes but the oil is under greater pressure than the coolant is, so the oil would "win" the battle of the two. although the pressure of the two does not mean anything when the engine is off.