2F compression numbers - how deep to go into engine?

[Ambrew]

Hi All,

did a compression test on an otherwise strong running engine. Did not open throttle, so that may be why it's a little low, did not do wet test either. Engine is now out of the truck since it needs new main seals, oil pan gasket, hard fuel lines and various other small bits. Apparently this truck sat for the better part of 10 years.

#1 135
#2 130
#3 105
#4 117
#5 130
#6 130

Head gasket? I was also wondering how to tell if valves are bad visually when the head is off. Any guidance/pictures would be nice.

I have a set of toyota gaskets on the way, but would like to save them for the restore. Felpro any good? I know the public opinion is to use Mr. T. gaskets, but any real life experience with aftermarket would be appreciated.

This is basically a comprehensive tune up, I will restore the truck in the future and just want to stop it pooling oil. It's getting new ignition parts, water pump, rad and the rest will be looked at. Trans and transfer getting new gaskets.

Thanks!


Andy

 

[LAMBCRUSHER]

stop.

adjust valves to .008 in, .014 ex @ cold
charge battery to full
block open throttle plate fully
remove all the spark plugs
test it again

report back the findings.

HTH.

 

[Ambrew]

Never spun an engine on a stand before.... Or should I lower it on a tire? and keep the crane on it?

 

[coonassjohn]

The engine should be warm when you do a compression test and Felpro gaskets are very good.

 

[pjohnson]

stop.

adjust valves to .008 in, .014 ex @ cold
charge battery to full
block open throttle plate fully
remove all the spark plugs
test it again

report back the findings.

HTH.

This ^^^^

Add a wet test also. You can do it on a stand if it's sturdy/stable enough, otherwise set it down attached to the hoist.

 

[thebigredrocker]

I had no idea what I was doing on my first compression test and got numbers like you posted. I didn’t allow the carb to breathe, had not adjusted valves with engine well warmed and had a intake manifold leak.

A later compression test with valves adjusted, carb open, fully charged battery, manifolds re-sealed, yielded 145-150 across the board.

If you wish to avoid unecessarilly tearing into engine, definately redo the comp test.

 

[Ambrew]

Yep. on it. will report.

 

[Ambrew]

I can get the starter to spin but it wont engage.....Voltage is 12.54. Perhaps the best way forward is to re seal the bottom end, and try the compression test when back in the truck?

Valves were good but then again motor cold.

 

[LAMBCRUSHER]

I’ve done it with oil in pan, pan on, chained to the hoist, resting gently on the ground. Hotwire battery direct to starter. Keep dizzy in so oil gets puMode.
Cold doesn’t matter as much as open throttle and adjusted valves. The value per cylinder is secondary vs the differential of all the values per cylinders...

 

[LAMBCRUSHER]

12.5 volts is about half dead...

 

[Ambrew]

Ok. I'll try again with another battery.

 

[Ambrew]

Lesson of the day: I have to engage the solenoid in order to get the starter to engage with the flywheel. that being said:

Adjusted valves
compression numbers:
Dry wet
145 150
135 140
100 110
110 110
130 130
135 145

suggestions please! Current thoughts: pull the head and get the valves done. take it from there.

 

[pjohnson]

Since it's already out and you're doing a re-seal anyway, I would pull the head and have a look inside.

 

[pb4ugo]

I'd put each of the weak cylders at tdc, and then apply compressed air thru the spark plug hole and listen to determine where the air is leaking. Pulling the head, valve job with resurfacing the head and new gasket would be good, but it may not solve the problem.

 

[Ambrew]

2f

• Ambrew
• Mar 27, 2018

all gasket scrapped. time for the fun stuff. The head is at a shop: 2 cracked seats and 6 new exhaust valves.

 

[Ambrew]

Ordered all the ''wear'' parts and getting it back together. I will try the Fel pro kit and see how it goes. I have a toyota gasket kit on order that i will stick in my hoard. As for paint, I've read a bit about the duplicolor and will give it a go, without the primer... since it's not available. This truck will get torn apart for a resto eventually, so I wont be horribly disappointed if something doesn't work out perfect.

Cleaned up oil pan bolts

Ready for oil pan

So I ordered a water pump, and got the wrong one. no biggie, i'll sell it. Ordered another one, paying more attention.... well it has the wrong flange. ugh. So, FSM, pullers and some heat and voila. Old flange on new pump. I also sealed the back of the pump from reading other threads...

 

[kcustom73]

Good to see things moving forward on your build. Looks like you're hustling to get her done. Good to see the engine stand being used

 

[Ambrew]

Yeah thanks for that... make the job way easier!

 

[emac]

keep it up! Did you rebuild the block?

 

[Ambrew]

Nope. I left the block alone. This was to be a re-seal only, but the compression numbers pointed to the valves. We'll see when it's all back together but from having looked at the valve