Current Events > Quick question. Told low psi in truck engine. Rebuild?

(+) Yeah! (+)

My mom took her truck in to the shop because she thought it was shifting hard and there was a transmission issue. They came back with it being a low psi in the engine not a transmission problem. The valves are fine, the seals are fine, the spark plugs are fine, pistons are fine. No leaks. Again supposedly. They told her she needs a rebuilt engine for $3500.

My gut reaction is that that doesn't sound right. There should be a reason for the low psi right? I fixable issue. Not just oh well you need a whole new engine. If there's low psi there has to be a cause.
I just don't want her to get hosed here and I don't know enough to say anything for certain but that's just me gut reaction. That she should go somewhere else. The thing is drivable anyway, it's just shifting hard.
---

Get a new truck?
---

Take this on over to the Car and Trucks board. You'll get an answer

But I assume by psi, you mean compression. Could come from a bad head gasket, piston rings, leaky valves, and whatnot.

Get a second opinion if you want as well
---

That would be my suggestion if it really is the engine. I don't think she's in the financial spot right now where she could though.

It's just that it being the whole engine doesn't seem right. Timing belt?
---

If its just one cylinder thats leaking, its probably a valve. If its two that are right next to each other, its probably a head gasket. If its more than that, you probably should replace it.
---

Low psi, or low compression would definitely indicate a piston, valve or gasket problem. Low oil or fuel pressure could be a culprit, but wouldnt really wouldnt affect the transmission complaints.
---

Low compression is not easily fixable. The cylinder walls are either scored or tapered out of shape from high mileage.

The engine must be fully stripped, the lower end rotating assembly (pistons, connecting rods, crank, etc) removed, and the block remachined.

However, low compression can be due to poor timing, although you'd see it across all cylinders and the engine would run very poorly.

Can be from a toasted head gasket if it has low compression on adjacent cylinders. This is worth checking as a head gasket is a far cheaper job than an engine reman.

What vehicle is it on?
---

EternalDivide posted...

That would be my suggestion if it really is the engine. I don't think she's in the financial spot right now where she could though.

It's just that it being the whole engine doesn't seem right. Timing belt?

A hard shift could just be the transmission searching for a lower gear to power the vehicle since the output of the engine is lower.
---

Many thanks.
She's going to get another opinion from a family friend mechanic I had totally forgot about.
---