Moving forward with the 325/454 - turning the beast

[Shinytoaster]

Hi all - we have a 1984 325 with a 30K mile 454, the one that cuts out unless the rpm are kept high.

Anyway, the current issue is I have ~90-100 psi in cylinder 5, the rest around 150 psi after a standard compression test.

I'm was set to do a leak down test today and came to a halt figuring out how to rotate the engine with all the shroud around the crank.

I read several blogs saying not to turn the main bolt going into the crank and several said 'bad idea' as it would strip the thread on the harmonic balancer (or likely too). Which was new to me having worked on older engines.

Sooo, how on earth do you manually turn the engine over with all the air shrouding there (and folks saying your shouldn't do that anyway)?

Option 1. take the starter off and rotate the flywheel with a breaker barl, otp. 2. maybe remove all the plugs and she'll turn over with a strap around the harmonic balancer ?

Any ideas - or am I just missing something?

Thanks-
Pete

[92landyacht]

I know of no reason to not use the crank bolt to turn the engine over as long as you turn the crank clockwise and turn it slowly.

[Shinytoaster]

Hi - thanks.

That was my initial thought but I've not done any engine work on these BB motors and some comments worried me about the harmonic balancer saying the thread wouldn't cope with the engine being rotated. Also - I have no idea how to get in there behind the plastic shrouding (it seems it would be a major effort to pull that out).

Originally Posted by 92landyacht

I know of no reason to not use the crank bolt to turn the engine over as long as you turn the crank clockwise and turn it slowly.

[dadstoy]

I recently did a compression check on mine...

Left Bank:
X
155
155
150

Right Bank:
155
160
150
140

I didn't check cyl 1 because I didn't want to crawl underneath at that moment to remove the spark plug.

I think 150psi is probably average so 90-100 is a bit low. I'm a little worried about my cyl 8 at 140psi.

I had tried to do a leak down test on cyl 8 but I could not get that cyl on TDC. I tried and tried and tried by bumping the starter.

I've never heard of such a thing of not using the crank bolt to turn the crank. That is a large bolt and requires 85lbft torque. You would never strip the threads. Just make sure you are not using any of the three small bolts that hold the pulley to the balancer...they are torqued to 35lbft. You would not strip them either but you could break them off. Maybe someone was talking about rounding off the head of the crank bolt. Doubtful that you would ever do that either. Use a 6 sided socket, not a 12 sided and it should not take that much effort anyway to turn the rotating assembly.

[Shinytoaster]

Thank you - what I was looking for. I can probably cut a hole in the plastic airflow/shroud if need be and turn from there... and patch it later. That would certainly make life a lot easier.

I'm just hoping the 90 psi in the one cylinder (of mine) is head related - otherwise a big/$$ job.

Cheers-
Pete

Originally Posted by dadstoy

I recently did a compression check on mine...

Left Bank:
X
155
155
150

Right Bank:
155
160
150
140

I didn't check cyl 1 because I didn't want to crawl underneath at that moment to remove the spark plug.

I think 150psi is probably average so 90-100 is a bit low. I'm a little worried about my cyl 8 at 140psi.

I had tried to do a leak down test on cyl 8 but I could not get that cyl on TDC. I tried and tried and tried by bumping the starter.

I've never heard of such a thing of not using the crank bolt to turn the crank. That is a large bolt and requires 85lbft torque. You would never strip the threads. Just make sure you are not using any of the three small bolts that hold the pulley to the balancer...they are torqued to 35lbft. You would not strip them either but you could break them off. Maybe someone was talking about rounding off the head of the crank bolt. Doubtful that you would ever do that either. Use a 6 sided socket, not a 12 sided and it should not take that much effort anyway to turn the rotating assembly.

[Shinytoaster]

FYI mine are at

8 - 153
6 - 140
4 - 152
2 - 155

7 - 144
5 - 90
3 - 148
1 - 155

So all in a reasonable range (~ <20%) bar cylinder 5 @ 90... darn

We'll see soon enough.

Pete

Originally Posted by Shinytoaster

Thank you - what I was looking for. I can probably cut a hole in the plastic airflow/shroud if need be and turn from there... and patch it later. That would certainly make life a lot easier.

I'm just hoping the 90 psi in the one cylinder (of mine) is head related - otherwise a big/$$ job.

Cheers-
Pete

[dadstoy]

Originally Posted by Shinytoaster

Thank you - what I was looking for. I can probably cut a hole in the plastic airflow/shroud if need be and turn from there... and patch it later. That would certainly make life a lot easier.

I'm just hoping the 90 psi in the one cylinder (of mine) is head related - otherwise a big/$$ job.

Cheers-
Pete

Hopefully there is a better way. I've been underneath and on top of the engine 1001 times but I haven't tried to get access to the crank bolt. I will do next time I visit the motorhome if the ground isn't too muddy. On my '82 I can remove the metal panel infront of the doghouse and access almost anything on the front of the engine. I will have to see if I can slip a breaker bar down to the crank bolt.

[Shinytoaster]

Hi, thanks for the photo, your engine bay is in a lot better shape than mine.. I like the blue!

I suspect the PO wasn't too interested in keeping her clean. The good news was I found the spark plug boot was almost rotted away so likely shorting; after replacing the plugs and leads (blue ) she fires up without any throttle first time (warmish here in central Florida), so that's nice.

You can see in the attached images mine needs work.. a long list, but getting there. Have the barn up, just waiting for the concrete floor to go in so I can start the bigger jobs. The floor will cost more than the RV, but it'll be great to have work space.

The scrap piece of paper was in the glove box under some trash, so I panicked when I first found it, but figure - if it was this engine it must have been done cold as my readings we significantly higher... and #6 magically had decent compression. Clearly the PO never showed me this. I figure I'd probably repower or rebuild this anyway so wasn't too worried.

Do you think having the original engine is a selling point from a collectors perspective? Certainly is for vintage/veteran cars, but doesn't seem to be here at least not that I have noticed. I'd probably keep it anyway (if I swap it out) and give to however buys it... might be in storage awhile tho'

Originally Posted by dadstoy

Hopefully there is a better way. I've been underneath and on top of the engine 1001 times but I haven't tried to get access to the crank bolt. I will do next time I visit the motorhome if the ground isn't too muddy. On my '82 I can remove the metal panel infront of the doghouse and access almost anything on the front of the engine. I will have to see if I can slip a breaker bar down to the crank bolt.

[vintage6t]

There should be a removable cover on the bottom front bell of the transmission. Remove the cover to expose the torque converter and flexplate. You can use a large screwdriver or prybar to rotate the engine via the starter teeth on the flexplate. Leverage in between a tooth on the flexplate and the transmission bell. Spark plugs removed so you're not fighting compression.

[Shinytoaster]

Thanks - I didn't realize that plate was removable.

I was hoping to avoid too muck skin loss leaning over the front of the engine so this is a good option - thank you!

Originally Posted by vintage6t

There should be a removable cover on the bottom front bell of the transmission. Remove the cover to expose the torque converter and flexplate. You can use a large screwdriver or prybar to rotate the engine via the starter teeth on the flexplate. Leverage in between a tooth on the flexplate and the transmission bell. Spark plugs removed so you're not fighting compression.

[92landyacht]

Now that you have her idling again, you might want to think about doing some Sea Foaming of the engine before you get too much into it. It's very possible that the low compression readings are coming from a stuck ring from sitting so long. That would explain why #6 now has better compression.

As for whether the stock engine is a plus or not... NOT. Unlike classic cars, owners of these motorhomes care more about future longevity than whether the numbers match or not. Personally, I would love to have one with an updated 8.1L engine or a 502HO.

[Shinytoaster]

I had forgotten I'd already done that a few months ago. I've always been wary of those mixes with old engines (80+ years) as sometimes the only thing holding compression is the gunge around the pistons/rings. So when parts aren't available or very hard to find it's a tricky call.

With the 325 that's probably what sorted out cylinder 6 (went from 40 up to 140) - maybe I should try another bottle.... be wonderful if it fixed # 5

Cheers-
Pete


an

Originally Posted by 92landyacht

Now that you have her idling again, you might want to think about doing some Sea Foaming of the engine before you get too much into it. It's very possible that the low compression readings are coming from a stuck ring from sitting so long. That would explain why #6 now has better compression.

As for whether the stock engine is a plus or not... NOT. Unlike classic cars, owners of these motorhomes care more about future longevity than whether the numbers match or not. Personally, I would love to have one with an updated 8.1L engine or a 502HO.

[Shinytoaster]

Originally Posted by 92landyacht

Personally, I would love to have one with an updated 8.1L engine or a 502HO.

Any preferences of the 502HO over the 502HT? My understanding was the HT was more of a 'truck' engine so was higher up the torque curve earlier in the rev range than the HO - maybe it doesn't matter so much?

With the connect and cruise option is sure gets pricy.

Pete

[chiefair]

I graphed the torque curves for the HO, HT and my original 454 to help with my decision. I posted the chart, it is post 24 on page 2 of the discussion of my 502 installation https://www.airforums.com/forums/f31...-140290-2.html

The HT has higher torque in the 2500-3200 range. The HO has higher torque from there up.

I chose the HO. I run over 3000 RPMs at highway speeds. I have plenty of low end torque and I am happy to have the increased torque when I needed it most - pulling hills at highway speed.

I have no lack of pulling power at lower speeds. I frequently tow my Jeep Wrangler through the mountains of NH and I am able to maintain traffic speeds.

[Shinytoaster]

Thanks - an interesting point. Pretty much all I've read says power are low revs is all that's needed but I can see the point of having more before up the rev range as well.

It's hard to get a feel for that in Florida as the 454 feels plenty powerful enough... no race car but gets going fine and gets over rolling hill with ease. Mountains tho' would be a different beast altogether.

When I tested the compression was way up on average, with cylinder 6 (40 to 140psi) and lifted cylinder #5 from 60 to around 90psi. So I thought that the previous test was possibly done on a cold engine, until it was suggested Seafood might help.... and I'd forgotten that I'd tipped in a bottle 3-4 months ago. I'm not sure of the differences between a hot and cold engine on compression so I really have no idea how much that first bottle of seafoam helped, tho' I suspect quite a bit.

Anyway - the first lot of seafoam I used was the liquid (not spray) and I just tipped it down the carb over a minute or two. Last night... after reading the directions some more... got the spray and sent that down... as per instructions this time. Not sure if it'll make much difference but we'll see soon. I can't really take it ou for a drive just yet as I haven't figured out why she randomly conks out... then runs again (appears to have plenty of fuel).

Not having to rebuild/replace/repower the beast would make the process of overhauling it much more appealing, at least give us a bit more time to consider options.

Thanks again all -
Pete

Originally Posted by chiefair

I graphed the torque curves for the HO, HT and my original 454 to help with my decision. I posted the chart, it is post 24 on page 2 of the discussion of my 502 installation https://www.airforums.com/forums/f31...-140290-2.html

The HT has higher torque in the 2500-3200 range. The HO has higher torque from there up.

I chose the HO. I run over 3000 RPMs at highway speeds. I have plenty of low end torque and I am happy to have the increased torque when I needed it most - pulling hills at highway speed.

I have no lack of pulling power at lower speeds. I frequently tow my Jeep Wrangler through the mountains of NH and I am able to maintain traffic speeds.

[martin300662]

Originally Posted by Shinytoaster

Thanks - an interesting point. Pretty much all I've read says power are low revs is all that's needed but I can see the point of having more before up the rev range as well.

It's hard to get a feel for that in Florida as the 454 feels plenty powerful enough... no race car but gets going fine and gets over rolling hill with ease. Mountains tho' would be a different beast altogether.

When I tested the compression was way up on average, with cylinder 6 (40 to 140psi) and lifted cylinder #5 from 60 to around 90psi. So I thought that the previous test was possibly done on a cold engine, until it was suggested Seafood might help.... and I'd forgotten that I'd tipped in a bottle 3-4 months ago. I'm not sure of the differences between a hot and cold engine on compression so I really have no idea how much that first bottle of seafoam helped, tho' I suspect quite a bit.

Anyway - the first lot of seafoam I used was the liquid (not spray) and I just tipped it down the carb over a minute or two. Last night... after reading the directions some more... got the spray and sent that down... as per instructions this time. Not sure if it'll make much difference but we'll see soon. I can't really take it ou for a drive just yet as I haven't figured out why she randomly conks out... then runs again (appears to have plenty of fuel).

Not having to rebuild/replace/repower the beast would make the process of overhauling it much more appealing, at least give us a bit more time to consider options.

Thanks again all -
Pete

Keep in mind your original 454 would be around 230hp, a modern build of the same engine is 440hp as well as over double the torque. There are 4 cylinder motors generating higher hp/torque numbers than the original engine.

If you tossed out the big block and installed a 350 HO you would have double the hp/torque than the original motor.

[92landyacht]

Originally Posted by martin300662

Keep in mind your original 454 would be around 230hp, a modern build of the same engine is 440hp as well as over double the torque. There are 4 cylinder motors generating higher hp/torque numbers than the original engine.

If you tossed out the big block and installed a 350 HO you would have double the hp/torque than the original motor.

Agreed that the new Gen 6 big blocks put out a ton more HP and Torque but....

Just keep in mind that most of the GM crate engines with higher HP numbers require the use of premium gas to maintain warranty.

If you can buy some time with your current engine, you can make a better long-term decision as to how much you're going to want to invest into her.

[92landyacht]

Pete, have you looked at all of the plugs to see what condition they're in? Oily or dry? Clean or Black? Expect the one with the bad plug wire to be black but dry.

Do the compression check warm. If you find a weak cylinder, then put a few drops of oil into it and test again. If compression goes up, then it's cylinder or ring issues. If no major improvement, then it's most likely a valve issue.

[jcslocum]

Here is a simple but effective flywheel turning tool.



https://www.amazon.com/DEF-Flywheel-...1746991&sr=8-7

Just do the leakdown on the one cylinder. You will probably have to hold the engine from turning when you do it. The air pressure will rotate the crank unless you have exactly on TDC for that cylinder.

Forgive me if you know the following and have followed it:

Compression test is done on a warm to hot engine
Battery on charger
All plugs out
Throttle propped wide open
Crank until the reading no longer rises

Good luck!!

[thewolffman]

Originally Posted by Shinytoaster

Hi all - we have a 1984 325 with a 30K mile 454, the one that cuts out unless the rpm are kept high.

Anyway, the current issue is I have ~90-100 psi in cylinder 5, the rest around 150 psi after a standard compression test.

I'm was set to do a leak down test today and came to a halt figuring out how to rotate the engine with all the shroud around the crank.

I read several blogs saying not to turn the main bolt going into the crank and several said 'bad idea' as it would strip the thread on the harmonic balancer (or likely too). Which was new to me having worked on older engines.

Sooo, how on earth do you manually turn the engine over with all the air shrouding there (and folks saying your shouldn't do that anyway)?

Option 1. take the starter off and rotate the flywheel with a breaker barl, otp. 2. maybe remove all the plugs and she'll turn over with a strap around the harmonic balancer ?

Any ideas - or am I just missing something?

Thanks-
Pete

Pete,
Don't turn the crank with a wrench or socket you'll kill yourself for no reason.

Start the engine and bring it up to normal operating temperature. After it cools enough put a pair of Mechanic gloves, mark all the plug wires remove them from the spark plugs and remove the sparks and mark which cylinder they came from.

Screw your compression gauge into the first cylinder. Have an assistant turn the engine over until you get the highest reading and record it, release the pressure and do all the cylinder the same way. All of the reading should be within 10-15% and the rear cylinders are usually the lowest. If one is below that reading a little 20-25%you might try an old mechanics trick or two. Sometimes they work sometimes not.

If any of the cylinders are low squirt one or two squirts of engine oil into that cylinder and turn it over real quick one time and repeat the compression test. If the reading gets then it means the rings are worn. If not it is a valve leakage problem. So what happens is sometimes carbon builds up on the face of the vales that seal the cylinder and the air leaks out during the compression stroke, hence low compression.

So try to clean the valves the old way.The first is put everything back together and take the top of the air cleaner and filter off the carburetor and start the engine and wait until it warms up.

Get a big water bottle and while you are manually holding the throttle at high idle (2,000 rpm+)slowly pour a small stream of water down the carburetor. The engine will cough and spit and want to stall but don't let that happen. Keep pumping the throttle to keep the engine running.
After a minute or two stop pouring the water and rev the engine until it stops coughing and spitting and see how it idles. Assuming the engine was misfiring and running rough at idle before with this procedure, since the compression was low, it will have smoothed out a bit after this procedure. If not do it again and again maybe three or four times, a couple of minutes each time. Basically you are trying to steam clean the carbon off the valve seats which sometimes works

Be advised you have an old steel engine which should be able to take this abuse. The only concern is a spark plug could crack and need to be replaced. After it cools do the compression test again and see if it helped.

If that does not help another thing you can do is remove the valve cover from the side of the engine that has the low compression, and stake the valves on that engine. So you are going to try to break the carbon off the valve by holding a 2x4 maybe 12" long long ways over the top of the valve and pound it with a large hammer (small 5lb sledge hammer works well) Strike each valve several times repeatedly. Every time you strike it you should hear the valve slam back onto the seat.

Repeat the compression test and say a pray. Maybe say a pray first. If none of this helps you either run it that way and live with it or take it to a real engine mechanic for a ring job or valve job or both. Actually I would not do that I would replace the engine entirely with the biggest cheapest crate engine I could find. Good Luck!

thewolffman