mother$hip89

Hello, I need some help with my engine. Here's some background: I was driving to work and my 350 blew off its hose. I didn't notice anything until it stalled at a light. I had been having issues adjusting the carburetor so I blamed that. I started it back up to find the engine would start to die at low rpm. I got to work a little further down the road and saw I left a trail of antifreeze. I instantly shut off the engine then turned the key back on to see the gauge wasn't showing too hot. I looked under the hood and saw the top hose off the radiator. I put it back on, refilled the coolant (wasn't actually that low) and changed the oil. The engine still gave me trouble at low rpm, and it seems worse when its warmed up. I pulled the motor and have removed the heads- the cylinders are not scored. What other damage could've happened from the lost coolant? Thanks in advance

olds 307 and 403

Potential bearing issues. Do you have an oil pressure gauge on the motor?

mother$hip89

I don't have an oil pressure gauge on it right now. How would I check the bearings?

Inline

Since you pulled your engine, turn engine up-side down, remove oil-pan, open the main-caps and connection rod-caps and look your bearings.

Btw, how much coolant you added? Since in case you lost alot of coolant, the engine is REALLY hot when temp-gauge starts to show overheat without coolant.

mother$hip89

Can I do this from underneath with the engine right side up, I'm gonna have some trouble getting it upside down.
Also, if I remember right it took just over a gallon. At no point did the gauge look like it was overheating.

joe_padavano

First, loss of coolant is highly unlikely to cause a bearing problem. The bearings are protected by the oil, not the coolant. Unless you lost oil pressure, the bearings are fine.

Second, scored cylinders would be my first concern. If you have verified this is not a problem, that's good.

Third, the most likely flaw is a blown head gasket. Unfortunately, you wanted to test for this before disassembling the engine. A leakdown test would have been the first thing to do. Now you should verify that the heads and deck on the block are flat before installing new head gaskets.

Fourth, a less likely (but non-zero) cause could be a crack (usually but not always in the head) that causes a loss of compression at temperature. Since the heads are off, you MIGHTASWELL have a machine shop go through them, including magnaflux and leak checking. That will answer any crack concerns.

I've found cast iron Olds motors are pretty tolerant of loss of coolant situations like this, at least when caught quickly. The fact that you tried to keep going may be the problem. Good luck.

oldcutlass

Check your radiator cap also, it should have released pressure before the hose blew.

joe_padavano

Not necessarily. If the hose clamp was loose, the hose will pop off at less than 15 PSI. It's happened to me.

Tedd Thompson

Also could have warped the valves.That also would give you a miss at low RPM.Is there oil in the water or water in the oil?..... Tedd

joe_padavano

Less likely than a head gasket but a definite possibility. All the more reason to have the heads checked.

mother$hip89

Ok so I need to get the heads checked out. As for making sure the surfaces are flat, is that something that can be easily done or will I need to get the shop to do that too? Also, I forgot to mention that everything got sprayed with coolant when the hose came off so is there anything I should check from that?

joe_padavano

Other than the mess, there's no issue with the coolant spray. The machine shop will check for flatness, but you can do it with a straight edge and a feeler gage. You can do the same for the deck surfaces of the block.

mother$hip89

Ok so I got some better lighting and I found some scoring, but I'm not sure if it's bad enough to be a problem. It looks a little worse in the picture than it is:

rustyroger

Not good. But the next step is removing the pistons and rods with a view to reboring. Your poor low speed running is almost certainly down to lost compression.
You might just need new piston rings and a glaze busting hone though.

To quote Jack Reacher; Hope for the best, prepare for the worst".

Roger.

mother$hip89

I had a shop check the pistons and bores. He wasn't that worried about the scratches on the cylinders but a few of the pistons were destroyed. Also, it turns out the rod bearings were wrecked and may have damaged the crankshaft.

olds 307 and 403

That sucks, it means the crank needs turned and you may as well do an overbore, get some quality forged pistons. What carb and how much timing? It sounds like detonation damage or severly lean. As far as bearing damage from overheating, my 403 had a perfect crank and bearings, very good oil pressure. After multiple over heatings, getting it home from my BIL's shop and then blowing a hose going back for tires. The crank and bearings, mains bearings especially, were very scored and showing copper in very few miles. It takes severe, multiple overheatings but it can happen, happened to me.

rustyroger

My guess on the bearing damage is pistons partially seizing rather than timing or carb suddenly gone bad.
If you need new pistons and a crankshaft reground you are close to the MAW rebuild the whole engine. How many miles are behind it?.

Roger.