Right track with plenum, heads, & cat?
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Registered User
Joined: Jan 2015
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Right track with plenum, heads, & cat?
Hey everyone, this is my first post!
Aaaannddddd.... I have a blown plenum, clogged cat, and loss of compression on #8 cylinder. In the last two weeks I have done a TON of reading on this forum on all of these topics. First I'd like to thank everyone who has contributed to the past conversations; I have learned a lot! But I'm also feeling a bit of info overload right now, and am a bit uncertain of myself. So, here is what I am planning to do, and I'd like you all to tell me if it looks like I'm missing anything or making a huge mistake. I'm planning to:
- install the Hughes plenum kit (it has not been done already)
- mod the kegger (mildly (probably mildly))
- install a 180* thermostat
- install Odessa heads (I am assuming at this point that mine are cracked)
- replace the timing chain (since I'm already in this far)
- remove the cat and replace with a y pipe that has holes for (new) 02 sensors (and spark plug non-foulers?)
Here are a few questions:
-Would the items above come with appropriate gaskets, or do I need to get a seperate gasket set? I've seen a lot of people recommending fel-pro gaskets, but I don't know if I need them or not.
- How long should all this take, working in my carport nights and weekends?
- What else am I missing? Is there anything else I may one day wish I had done while I'm in here?
I've replaced plenty of parts in the past, altenators, water pumps, and such. I have never tried anything quite this "deep" before, but I have always wanted to. I do like a good challenge....
Any help is appreciated!
Aaaannddddd.... I have a blown plenum, clogged cat, and loss of compression on #8 cylinder. In the last two weeks I have done a TON of reading on this forum on all of these topics. First I'd like to thank everyone who has contributed to the past conversations; I have learned a lot! But I'm also feeling a bit of info overload right now, and am a bit uncertain of myself. So, here is what I am planning to do, and I'd like you all to tell me if it looks like I'm missing anything or making a huge mistake. I'm planning to:
- install the Hughes plenum kit (it has not been done already)
- mod the kegger (mildly (probably mildly))
- install a 180* thermostat
- install Odessa heads (I am assuming at this point that mine are cracked)
- replace the timing chain (since I'm already in this far)
- remove the cat and replace with a y pipe that has holes for (new) 02 sensors (and spark plug non-foulers?)
Here are a few questions:
-Would the items above come with appropriate gaskets, or do I need to get a seperate gasket set? I've seen a lot of people recommending fel-pro gaskets, but I don't know if I need them or not.
- How long should all this take, working in my carport nights and weekends?
- What else am I missing? Is there anything else I may one day wish I had done while I'm in here?
I've replaced plenty of parts in the past, altenators, water pumps, and such. I have never tried anything quite this "deep" before, but I have always wanted to. I do like a good challenge....
Any help is appreciated!
Professional
Joined: Feb 2015
Posts: 178
Likes: 0
Welcome and thanks for the compliments.
First off, a 180deg stat will do nothing but make the truck run rich, beast to stay with a stock temp, probably 195. Secondly, it's not real common that the heads crack, you need to do an actual leak down test to see why you have low compression in #8 cylinder. If you don't have a leak down tester you can do it with a compression tester hose with the valve removed and about 15psi of air pressure running through it. Fill the cylinder with the valves closed (at TDC or loosen off the rockers) and listen for the air escaping, if you hear it in the intake or exhaust it's a valve/head issue, if it comes out the rad it's probably cracked, if it's in the oil pan it's in the bottom end.
Finally, it's tough to say how long without knowing your skill level and the equipment you have. It would probably take a good tech 6-8 hours to do all that work with the right tools and equipment.
First off, a 180deg stat will do nothing but make the truck run rich, beast to stay with a stock temp, probably 195. Secondly, it's not real common that the heads crack, you need to do an actual leak down test to see why you have low compression in #8 cylinder. If you don't have a leak down tester you can do it with a compression tester hose with the valve removed and about 15psi of air pressure running through it. Fill the cylinder with the valves closed (at TDC or loosen off the rockers) and listen for the air escaping, if you hear it in the intake or exhaust it's a valve/head issue, if it comes out the rad it's probably cracked, if it's in the oil pan it's in the bottom end.
Finally, it's tough to say how long without knowing your skill level and the equipment you have. It would probably take a good tech 6-8 hours to do all that work with the right tools and equipment.
Administrator
Joined: Apr 2010
Posts: 87,465
Likes: 4,220
From: Clayton MI
99% of the time, gaskets are NOT included. (except for things like water pumps....) Make sure you get good quality gaskets.
Think I would do a leakdown test on at least #8, to see where your compression was going. Might be a bad valve, might be a holed piston... need to know before spending money, and then finding that it won't help.
To do heads, intake, timing set (double roller please), I would guess around 15-20 hours, if things go reasonably well. Having access to air tools makes the job MUCH easier.
Might wanna see if you can find another intake from the same year truck, and mod that one. I spent quite a few hours on JUST doing my manifold...... If you aren't too far away, I have a spare sitting in the garage.
Unless you are doing a tuner as well, stick with the 195 'stat. (also depends a lot on where you live.)
Welcome to DF!
Think I would do a leakdown test on at least #8, to see where your compression was going. Might be a bad valve, might be a holed piston... need to know before spending money, and then finding that it won't help.
To do heads, intake, timing set (double roller please), I would guess around 15-20 hours, if things go reasonably well. Having access to air tools makes the job MUCH easier.
Might wanna see if you can find another intake from the same year truck, and mod that one. I spent quite a few hours on JUST doing my manifold...... If you aren't too far away, I have a spare sitting in the garage.
Unless you are doing a tuner as well, stick with the 195 'stat. (also depends a lot on where you live.)
Welcome to DF!
Champion
Joined: Feb 2005
Posts: 3,710
Likes: 2
From: Skagit County, WA
I wouldn't say it's uncommon for these heads to crack. When I pulled the heads off my old Dakota 5.9, 6 cylinders had cracks between the valves.
But that's not to say the cracks were a problem. It had head gasket issues, and the cracks were found while inspecting the heads after removal.
But throwing heads on an engine with a wiped out cylinder won't make it better. You may need to freshen up the bottom end and rotating stuff too.
But that's not to say the cracks were a problem. It had head gasket issues, and the cracks were found while inspecting the heads after removal.
But throwing heads on an engine with a wiped out cylinder won't make it better. You may need to freshen up the bottom end and rotating stuff too.
Professional
Joined: Jan 2011
Posts: 200
Likes: 0
Welcome and thanks for the compliments.
First off, a 180deg stat will do nothing but make the truck run rich, beast to stay with a stock temp, probably 195. Secondly, it's not real common that the heads crack, you need to do an actual leak down test to see why you have low compression in #8 cylinder. If you don't have a leak down tester you can do it with a compression tester hose with the valve removed and about 15psi of air pressure running through it. Fill the cylinder with the valves closed (at TDC or loosen off the rockers) and listen for the air escaping, if you hear it in the intake or exhaust it's a valve/head issue, if it comes out the rad it's probably cracked, if it's in the oil pan it's in the bottom end.
Finally, it's tough to say how long without knowing your skill level and the equipment you have. It would probably take a good tech 6-8 hours to do all that work with the right tools and equipment.
First off, a 180deg stat will do nothing but make the truck run rich, beast to stay with a stock temp, probably 195. Secondly, it's not real common that the heads crack, you need to do an actual leak down test to see why you have low compression in #8 cylinder. If you don't have a leak down tester you can do it with a compression tester hose with the valve removed and about 15psi of air pressure running through it. Fill the cylinder with the valves closed (at TDC or loosen off the rockers) and listen for the air escaping, if you hear it in the intake or exhaust it's a valve/head issue, if it comes out the rad it's probably cracked, if it's in the oil pan it's in the bottom end.
Finally, it's tough to say how long without knowing your skill level and the equipment you have. It would probably take a good tech 6-8 hours to do all that work with the right tools and equipment.
Thread Starter
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Registered User
Joined: Jan 2015
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Thanks for the input, guys. Sorry it's taken me awhile to get back but I've been sick the past couple of weeks and just haven't been up to it. So I had a local shop test #8 cylinder, he says the problem is in the head. He didn't say for sure it's cracked, be he said it probably is.
I'm getting some conflicting info on whether these heads are prone to crack or not. If they are, I want to put something on that's not prone to crack. Anyone else want to chime in on this? Also, conflicting info on the thermostat. Thanks Tweeker909 for the link, I've found some good info there. I'm not sure I understand how swapping a different thermostat could cause the engine to run rich? Wouldn't this just make it run cooler?
I'll add the fel pro gaskets to my shopping list.
So looking over what I am planning at this time, does anyone have any additional advice? Anything else I should be looking at while I'm in this far?
I'm getting some conflicting info on whether these heads are prone to crack or not. If they are, I want to put something on that's not prone to crack. Anyone else want to chime in on this? Also, conflicting info on the thermostat. Thanks Tweeker909 for the link, I've found some good info there. I'm not sure I understand how swapping a different thermostat could cause the engine to run rich? Wouldn't this just make it run cooler?
I'll add the fel pro gaskets to my shopping list.
So looking over what I am planning at this time, does anyone have any additional advice? Anything else I should be looking at while I'm in this far?
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Grand Champion
Joined: Apr 2010
Posts: 5,011
Likes: 6
From: Meeker, CO
It won't. I believe that myth is rooted in ignorance of the causes of engine knock. I could be wrong about the origin of the myth.
Did your shop say where number 8 cylinder is leaking to? Throttle body or tail pipe?
Don't buy anything until you pull the failed head and visually confirm the failure. Then go from there. As stated there may be more to it than a top end rebuild.
Don't buy anything until you pull the failed head and visually confirm the failure. Then go from there. As stated there may be more to it than a top end rebuild.