Head gasket and exhaust gasket questions, and finding TDC

[BubbaFL]

I'm getting ready to put my SOHC back together and have a couple questions:

#1 - Is this stuff good to use on the headgaskets? permatex copper spray a gasket

#2 - Would that stuff be good on the exhaust manifold gaskets? The stock gaskets were thin metal pieces (several on each side). The new exhaust gaskets are some kind of plastic / composite.

#3 - When I'm finding TDC on the number 1 cylinder to set the timing, how precise does it need to be? The crank turns several degrees with no apparent piston movement - do I want to be at the beginning, middle, or end of that range?

Thanks!

 

[2000StreetRod]

TDC accuracy

It is not that critical to find TDC exactly when assembling the engine. A few degrees off will not be a problem. Note the crank position where the piston stops moving and then starts moving and set the crank for the middle of the two points. After the front timing cover and balancer are installed you'll want to be as accurate as possible in setting the #1 piston at TDC on the compression stroke for timing the camshafts. I assume that you have access to the OTC-6488 tool set and the instructions for timing the camshafts.

 

[JDraper]

Most head gasket sets recommend you do not use any sealer/spray on them. I wouldn't use it unless the gasket manufacturer recommends it.

 

[BubbaFL]

Dale:

I don't have the OTC-6488 toolkit; after reading your threads a dozen times it seems simple enough and I'm going to give it a shot without it.

I just need to set #1 at TDC, get both camshafts aligned so that the notches at the back are parallel with the head and below the centerline, lock everything in place with vise grips and clamps, and tighten it up, right?


JDraper - my gasket set didn't come with any instructions. I'm leaning towards using one of the spray sealers just for good measure. Could it cause problems?

 

[2000StreetRod]

Chain tensioner

Dale:

I don't have the OTC-6488 toolkit; after reading your threads a dozen times it seems simple enough and I'm going to give it a shot without it.

I just need to set #1 at TDC, get both camshafts aligned so that the notches at the back are parallel with the head and below the centerline, lock everything in place with vise grips and clamps, and tighten it up, right? . . .

You need some way to tension the camshaft chain when aligning the camshaft slot. The spring in the hydraulic tensioner is not strong enough to make the chain taught when setting the timing. Did you purchase a new left hydraulic tensioner? If so, you can use the old one as a substitute for the calibrated tensioner included in the OTC-6488 kit. But first you'll have to clean it and epoxy the piston so it will not move relative to the housing. I used my old rear hydraulic tensioner but it is almost too short to use on the front. The photo below shows the rear tensioner converted to a tensioner tool.

The arrows indicate where the epoxy was applied. You should use an in-lb torque wrench when installing the tensioner tool. It needs to be tight enough to make the chain taught but not so tight to break the guide assembly.

Make sure the jackshaft front sprocket retaining bolt is torqued and the primary tensioner pin is pulled before installing the front timing cover.

 

[BubbaFL]

More Gasket Questions

Any guesses on what these various gaskets and washers are for? My set came with no instructions.

Set #1

Set #2

Next question: the water pump and timing cover gaskets have some kind of rubbery red bead in the middle. Do I still need to use RTV on this kind of gasket?

(click for big pic)

Last question (for now):

There's a metal "thing" on the block where the timing cover bolts up. Is this a gasket that needs to be scraped off, or should it stay on? It's stuck pretty good so I didn't want to tear it up if it needs to stay in place.

(click for big pic)

Thanks!

 

[2000StreetRod]

front timing cover gasket

. . . There's a metal "thing" on the block where the timing cover bolts up. Is this a gasket that needs to be scraped off, or should it stay on? It's stuck pretty good so I didn't want to tear it up if it needs to stay in place.
Thanks!

That's the old front timing cover gasket that should be scraped off. Make sure that you have a replacement gasket.

 

[BubbaFL]

Still having problems here

I have the heads back on, everything lined up and tightened down - crankshaft keyway straight up, slots on both cams parallel to the head and below the centerline.

I'm getting no measurable compression on any cylinder.

When I had the heads off, the pistons looked perfect, and I didn't see any visible damage to the valves. Is it possible to damage the valves without leaving any marks on the pistons?

Any ideas on where to go from here?

 

[2000StreetRod]

camshaft rotation?

I assume that you still have the valve covers off. Are the camshafts rotating when you rotate the crankshaft? No compression on any cylinder could be due to a loose front jackshaft sprocket. Did you torque it properly before installing the front cover and harmonic balancer? It could also be due to no (or a broken chain) between the crankshaft sprocket and the jackshaft sprocket. Did you torque the camshaft sprocket retaining bolts?

What did you do (if anything) to the heads? Were the camshafts, rocker arms, lash adjusters, valve springs or valves removed?

If the valves have struck the pistons it is usually the exhaust valves and there will be a curved mark on the top of the pistons from the valves.

 

[BubbaFL]

All of the chains are in place and torqued down. The crankshaft keyway and slots on the camshafts all appear to be where they're supposed to be:

Here's what the pistons looked like before I put the head back on:

and there was no visible, obvious damage to the valves:

I didn't do anything to the heads other than take them off, look for damage, clean them up, and put them back on.

I'm out of my league here - is there anything else I can do to tell whether or not the valves really are bent, other than putting it in the truck and trying to start it or sending the heads off to a machinist?

Edit: I did a home-made leakdown test using the gauges on my air compressor - #1 was 20% and #4 was 10% - seems like maybe everything is in order? Maybe I'm just not turning the crank fast enough to get a reading with a normal compression test?

 

[2000StreetRod]

oil the cylinder?

The photo does not show any obvious sign of valve/piston collision. I can't tell from the photo which bank of pistons are shown. Here's the results of a 50 degree slip on the right bank.

You might try adding 1 teaspoon of engine oil thru the spark plug port, crank the engine by hand for at least 4 revolutions, insert your compression tester and check for an improvement.

Do you have any oil in the pan? The valve lash adjusters are hydraulic and may have lost their oil resulting in reduced movement. Also, cranking the engine with no oil in the pan will cause the oil pump to lose its prime.

 

[BubbaFL]

The photos show the right bank and right head; the left looked the same.

The engine is still on a stand - the oil pan's not attached yet. I did spray wd-40 into the cylinders to lube them up before trying to set the timing and check compression.

 

[BubbaFL]

She runs! Sounds like crap though:



Any guesses what that noise might be? No check engine light, idle seems reasonably smooth, oil pressure is good.

 

[2000StreetRod]

compression check

It doesn't sound good. Now that you have it running I suggest another compression check with all plugs removed and the throttle plate wide open. If all the cylinders have good compression then try to identify the noise source location. I use a flexible hose held to my ear while moving the other end around the engine compartment. I haven't had much luck using my mechanic's stethoscope.

 

[BubbaFL]

YEAH BABY!



The audio quality is crappy - she purrs like a kitten now!

The oil dipstick tube was bent, I guess the crank was rubbing on it.

 

[2000StreetRod]

Congratulations!

When the engine is started after being torn down it is noisy because the hydraulic lash adjusters and the hydraulic timing chain tensioners aren't filled with oil. I'm glad you got it quieted down and I hope it gives you many years of trouble free service!

 

[BubbaFL]

Well, she gave me 24 hours (and 5 minutes driving time) of trouble free service.

Looks like the new rear main seal I installed is leaking like crazy - oil coming out of the bellhousing and around the starter.

So do I pull the tranny and redo the rear main (or maybe the upper oil pan gasket) or throw a bottle of Bars in there and see if that fixes it?

 

[2000StreetRod]

Engine oil or ATF?

I'm sorry to hear about your leak. I suggest that you make sure the oil is from the engine and not the transmission. Sometimes removing and installing the engine can damage the transmission front seal.

Several members have experienced engine oil leaks after replacing the rear main seal. When I replaced mine I noticed that the block section around the crankshaft was not even with the reinforcement section around the crankshaft. The installation instructions emphasize that the face of the seal must be perpendicular to the axis of the crankshaft. I think some members install the seal to be flush with the upper and lower sections resulting in a non-perpendicular seal. Rear main seal replacement preparations and
Replacing rear main seal

It is very difficult to determine if the main seal or the reinforcement gasket is leaking without separating the transmission from the engine.

 

[BubbaFL]

On further inspection, I'm not sure if the rear main seal is leaking.

I noticed what appeared to be little puddles of fuel around the injectors on the left bank, so I pulled the upper and lower intake. Once I had the lower off, I could see that the valley between the cylinder heads is FULL of oil (at least a pint just laying there). It looks like the oil filled up the valley and then was running down the back of the motor.

Anybody have ideas where the oil could be leaking?

The valve cover gasket is new and the bolts are torqued to spec.

There is no trace of oil around the front hydraulic tensioner, so I don't think that is leaking.

Other than those two places, is there anywhere oil could leak and end up around the injectors on the left side, and in the valley?

Here are a couple pics showing where the oil is pooling.

Would it be safe to crank the motor with the upper and lower intake off, if I disconnected the spark plug wires and pulled the fuel pump relay? Maybe if I crank it and build up oil pressure I could see the leak.

 

[2000StreetRod]

Crankcase breather?

Did you remove the crankcase breather? If so, did you reinstall it?