New member 1st gen - already fearing the worst :(

[nordon]

Hello everybody! I just purchased an 1986 auto, and as I initially thought it was a steal at $2k with 130000 miles, I drove it home and immediately realized it almost certainly has a blown HG... I'm kicking myself for not spending a bit more time with the vehicle before purchase but what's done is done. I'm a bit excited to do the work, but I'm concerned that more damage to the engine was done, as I don't know how long the vehicle had been driven in it's current state. The temp gauge on the drive home showed normal, but I'm not sure where the sender is located, so I'm worried the coolant was gummed up from oil and maybe not flowing properly (please let me know if my suspicions are unfounded) and the oil pressure gauge was low the entire trip home (registering, but low) -- I had ignorantly assumed it was the oil temperature....
So sorry to start my first post so sorely, Do you all think there are any grounds for my concerns for further engine damage, and what would be the best way to assess?

 

[Quatre Coureur]

Welcome aboard. Diggin those 'tube' bumpers! Don't worry about the oil pressure being low, that's normal.

 

[KidVermicious]

Do you all think there are any grounds for my concerns for further engine damage, and what would be the best way to assess?

It's possible. What's it doing that makes you think the head gasket is gone? Are you overheating? Mixing oil and coolant? What do the spark plugs look like? A compression test will tell you a lot, a leakdown test will tell you more.

It's possible that your head gasket is fine and what you've got is a hole in the timing chain cover, that's common with these motors when you go past the service interval and wear the timing chain guides out. The oil pump normally gets changed when you do the timing chain, so if neither has been done in a blue moon that could be your problem. If it overheated badly or you've got too much coolant in the oil that could have trashed your bearings, and that'd cause low oil pressure too.

Run some basic tests, then drop the pan to check the bearings and pull the timing cover to see what shape your chain and guides are in. Then go from there. But if you intend to drive this truck for a while, my advice would be to get a full rebuild kit from ENGNBLDR.COM, ENGINE PARTS NETWORK and plan on rebuilding the entire motor on general principles.

Your oil pressure sender is on the passenger side of the block just above the oil filter, btw.

 

[nordon]

Thank you for your insight. I'm not seeing any Coolant in the oil, just oil in the coolant. And there is an oil sludge coming from the coolant reservoir overflow. I plan on doing a compression test this weekend and a leak down test if the compression is poor.