Down on power, sounded different.

[Terry Wilkerson]

A week ago my truck sounded like air leaking a little and seemed down on power. My grandson was driving so really not sure about the power. I read a thread about valve train problems. I hooked up a vacum guage to it. When first started it was just in the Lateing Timing red. After it warmed up it was in the Normal Motor. I read where the needle should be steady. The needle was moving 1 to 2 marks on the guage. Is this enough to indicate a problem?

 

[Terry Wilkerson]

Also it sounded normal today.

 

[QBuff02]

Vac Visual: Quick Guide to Vacuum Gauge Readings - OnAllCylinders

Intake manifold vacuum is a key indicator of engine performance. By measuring vacuum under different engine loads and conditions, you can track down problems within your engine and make the …

www.onallcylinders.com

Read this article and reference what your vac gauge was doing and then you'll have an idea where to more closely inspect/troubleshoot.

 

[Vbb199]

I was thinking a consistently moving vacuum gauge in the same area was valve leaks, or I guess I should say, valves not sealing.

You said it maybe lost power, your answer may lie there?

Loose rocker arm? Broke spring? Bent pushrod? Flattened lifter or cam lobe?

Let's hope not

 

[dvdswan]

How many miles are on the engine? Is it fresh, 100K, 200K? Possibilities of build up on the valve seats? Vacuum hoses hard or cracked? Timing set correct, when was it last checked?

Often too long, owner's will mistake a properly functioning fan clutch as a loss of power or slipping transmission.

 

[AyWoSch Motors]

Air leaking? Could it be vacuum leak?

 

[shiftpro]

Broken spring, pin or seized weight in the dizzy.

 

[Bextreme04]

A fluctuation in the vacuum gauge is due to one cylinder not functioning properly. This can be for many reasons. Worn cam lobe, mis-adjusted valve train, broken valve spring, broken piston rings, worn/leaking valves, etc...

 

[Terry Wilkerson]

I bought new valve cover gaskets. So I'll be looking in to the top of the head and check for all the things mentioned. I knew things were going to smooth. It's part of the territory when driving a classic.

 

[Vbb199]

Ain't that the truth ^^

 

[Jacob Miller]

Last time I was down on power I found this joy in the top end, keep in mind my vac gauge was swinging wildly at idle, couldn’t really call it an idle tho lol.

 

[Terry Wilkerson]

Ok so I'v been crazy busy lately. This morning I removed the valve covers. No broken spring or anything else I can see. I adjusted the valves. Cylinder #3 had a small amount of water come out as I rotated the engine to set valves. Can a intake gasket let water into the cylinder? The reason I ask is I have had coolant on the top of the motor along the intake and the head for a while. I had trouble getting the upper hose to seal at the thermostat housing and thought that was the source of the coolant on top of the motor. Maybe gasket all along??
Maybe a compression check next. What ya think?

 

[Bextreme04]

Ok so I'v been crazy busy lately. This morning I removed the valve covers. No broken spring or anything else I can see. I adjusted the valves. Cylinder #3 had a small amount of water come out as I rotated the engine to set valves. Can a intake gasket let water into the cylinder? The reason I ask is I have had coolant on the top of the motor along the intake and the head for a while. I had trouble getting the upper hose to seal at the thermostat housing and thought that was the source of the coolant on top of the motor. Maybe gasket all along??
Maybe a compression check next. What ya think?

Not into only #3. The only way I can imagine coolant getting into ONLY #3 would be a cracked head, cracked block, or blown head gasket.

Its also possible that a bad intake gasket could let pooled water on top of the intake/head gap leak into the intake port. Not very likely, but possible.