Volvo head gasket?-gctid822342

[Mrich]

Hello -I finally did compression check on no start Volvo AQ131 and had about 95 in the 2 aft cylinders others 130, 150. I've read this points to head gasket . There are many things I enjoy more than working on an engine but out of necessity( the boat mechanics near me are scared of this Swedish thing even though it's basically a car motor with easy access- else I'd gladly pay them) I've replaced both pumps on this and I've replaced the valve cover gasket on my car but this seems much more involved.I have Clymer( not the greatest) manual and the 98 pg Volvo workshop manual( not super specific)

My question to someone who has changed the head gasket on this or it's cousins-How long would this take and could someone with average mechanical skills who took their time do this? I don't see any special tools needed . Is there better, detailed, specific guidance elsewhere? Also if it is the head gasket would that prevent it from starting? (It turns and I've replaced plugs, points,coil wires,fuel etc.)

Thanks. Sorry for ramble....

[Pcpete]

It's mostly a nut and bolt thing with care on disassembling and re assembling the larger pieces. Break all of the nuts and bolts just a bit loose on an assembly and back them all off evenly rather than completely removing one before going to the next. The same applies during assembly. If you don't have a torquing sequence work from the center out.

That engine should start with those compression numbers. Have you checked the timing chain to ensure it has not slipped? I'm thinking that's an overhead cam engine. Also, how is the distributor timing? Could you be 180 degrees out? Checking that is a matter of rotating the engine until you see the valves on the number one piston are both closed and the timing mark on the harmonic balancer is at top dead center. The distributor rotor should be pointing dry close to where the number one plug wire plugs into the cap. Getting more basic, do you have spark? You should be able to spin the motor and see the points snapping, then, using a timing light, see the flash as number one fires. Then you can point the light at the timing mark to see where you are against the basic 8 degrees or so before top dead center. If it's close, rotate the distributor a few degrees, one way then the other, while spinning the engine and all things being equal, it should start. It may backfire a time or two but if it has fuel and spark it ought to start.

Add where you live to your signature, it may be that I, or another member, live right up the street.

[alanmoor]

I just did this on my motor (I got the heads rebuilt). The last serious engine work I did was when I was 16 and rebuilt my motorcycle engine. I used my Clymers, this forum, and google. I would say you could do it in a day but I came and went on the project, spending a few hours at a time. I think I spent as much time doing research as I did doing the work.

I don't want to insult your intelligence but here are a few things I learned:

Get a bunch of coffee cans (like 10) to put parts in. I could have used more than I had so I could separate everything out by where it goes on the engine.

You should organize the push rods and valves so they go back in the same cylinder and intake/exhaust. Some people use a strip of cardboard for this.

Be sure you have a tap and die set to clean out your head bolts and their sockets. I put everything together and even adjusted the valve lash (which was the most time consuming) and pulled the heads back off because I thought about it overnight and decided I didn't like how the head bolts went in. Use thread sealant on the head bolts.

Don't forget to re-torque the intake manifold after running the engine (and it's cold). You should do this 2-3 times. I think not doing this is what caused my intake manifold to fail.

Don't forget to get the torque values for your carburetor.

Get a click type torque wrench (I started with one with a lever, what a PIA and not accurate). Clymers will give you the pattern and torque values to tighten the head bolts. I used the intake manufacturer's directions to torque the intake.

I did mine without pulling the engine, but I have a roomy engine compartment. Even with that, I question whether it would have been easier if I had pulled the engine, so you might think about that. I'm a big guy, and contorting myself around the engine made me a yoga expert.

Before you pull the heads you might want to try a leak down test - this might tell you if it is a head gasket or valves. In my case it was valves (the intake manifold gasket leaked and overheated the intake valves).

I'd be surprised if the head gasket prevented it from starting but I suppose it's possible. It sounds like yours is in as bad a shape as mine was and I was using mine, it would start right up but it had no power.

Lastly, don't take anything I write ask gospel, I'm only relaying information based on my one time experience, not my expertise!

As Pcpete said, put your location in your signature... I have a leak down test kit I've been dying to use successfully! I used it on a "dry" engine which goes you bad readings.

[88fourwinns]

"alanmoor" post=822399 wrote:
I just did this on my motor (I got the heads rebuilt). The last serious engine work I did was when I was 16 and rebuilt my motorcycle engine. I used my Clymers, this forum, and google. I would say you could do it in a day but I came and went on the project, spending a few hours at a time. I think I spent as much time doing research as I did doing the work.

I don't want to insult your intelligence but here are a few things I learned:

Get a bunch of coffee cans (like 10) to put parts in. I could have used more than I had so I could separate everything out by where it goes on the engine.

You should organize the push rods and valves so they go back in the same cylinder and intake/exhaust. Some people use a strip of cardboard for this.

Be sure you have a tap and die set to clean out your head bolts and their sockets. I put everything together and even adjusted the valve lash (which was the most time consuming) and pulled the heads back off because I thought about it overnight and decided I didn't like how the head bolts went in. Use thread sealant on the head bolts.

Don't forget to re-torque the intake manifold after running the engine (and it's cold). You should do this 2-3 times. I think not doing this is what caused my intake manifold to fail.

Don't forget to get the torque values for your carburetor.

Get a click type torque wrench (I started with one with a lever, what a PIA and not accurate). Clymers will give you the pattern and torque values to tighten the head bolts. I used the intake manufacturer's directions to torque the intake.

I did mine without pulling the engine, but I have a roomy engine compartment. Even with that, I question whether it would have been easier if I had pulled the engine, so you might think about that. I'm a big guy, and contorting myself around the engine made me a yoga expert.

Before you pull the heads you might want to try a leak down test - this might tell you if it is a head gasket or valves. In my case it was valves (the intake manifold gasket leaked and overheated the intake valves).

I'd be surprised if the head gasket prevented it from starting but I suppose it's possible. It sounds like yours is in as bad a shape as mine was and I was using mine, it would start right up but it had no power.

Lastly, don't take anything I write ask gospel, I'm only relaying information based on my one time experience, not my expertise!

As Pcpete said, put your location in your signature... I have a leak down test kit I've been dying to use successfully! I used it on a "dry" engine which goes you bad readings.

This advice is right on esp with regard to the cleaning of the bolt holes in the cyl head.for this Id use a thread chaser rather than a tap. This and keeping dirt out of everything is very important. To this I'll add pick up a good precision straight edge and a good set of feeler gauges. You will need these to measure the block, head and intake sealing surfaces for flatness usually less than .004"...

[2850Bounty]

FYI: The OP is asking about the Volvo Penta AQ131 4 cylinder overhead camshaft engine.

There is only one cylinder head on this engine, and there are no push rods.

Yes..... do not use a thread tap to chase the female threads. Use a proper tool or a roll-thread tap.

Yes...... there appears to be enough cylinder pressure for this engine to fire up on. This is why I suggested earlier to look at the timing belt indexing!



.

[Mrich]

Checking that is a matter of rotating the engine until you see the valves on the number one piston are both closed and the timing mark on the harmonic balancer is at top dead center.

How exactly do I do that? Thanks for the reply

[2850Bounty]

This cogged belt drives two components;

One...... the counter-shaft which operates the ignition distributor, the fuel pump and the engine oil pump and also the seawater pump .

And two, the camshaft and all valves.

Do yourself a favor and purchase the Volvo Penta OEM workshop manual. It will demonstrate how to index the belt and driven pulleys.

.

[Pcpete]

The easy way imo is to remove the spark plugs and valve cover. Rotating the engine with a socket wrench on the harmonic balancer bolt is my usual way of watching the valve train work. If you doubt the way it should spin, give the starter a bump. As you rotate the engine you will see the number one valves open and close. Rotate the engine and watch the exhaust valve open as the piston comes up then close as the intake valve opens the piston bottoms and begins the compression stroke. When the timing mark is at top dead center and both valves are closed the rotor on the the distributor should be just past the number one pin in the distributor cap.

Here's a YouTube that is for a fancy v8 but the process is the same. https://m.youtube.com/watch?v=vuQRxElSZ3c

[Mrich]

Thank you, I really appreciate it.

[2850Bounty]

Pete, that is a great procedure for an engine with a chain and sprocket driven camshaft.

With this OHC engine, if the timing belt has not been indexed correctly (or if it has slipped)..........., he will not be able to rely on the position of the valves nor the position of the rotor.

The OEM workshop manual explains the "how to" in text and with illustrations.

.

[Pcpete]

I couldn't find a video that was exactly like his so I went for theory. I agree that the whole thing could be off but if the crank and cam don't line up with tdc in either crank rotation then there's the place to start. I'd love to be getting my hands dirty on this but right now we have a couple of Dungeness crab on the stove. Ah, the choices....

[Terry_J]

You might want to buy a new timing belt kit for it. Should be around $50 and comes with a new idler bearing. The instructions that come with the belt take you step by step through the process. The new belt has 3 marks on it that you need to line up. I doubt you'll find those marks on your old belt.

Terry