Bad motor?

[waynehartwig]

I've been digging into my motor over the past couple of months trying to figure out why it runs hot... I haven't done much as I haven't had the time to divulge.

I pulled the plugs and 1-3 had a nice brown core with a bit of black soot on the threads. 4 was white porcelain. 5 was fouled with a brown build up - carbon? It wasn't oil, it was brown and porus. 6 looked like 1-3 but without the black soot.

Ok, so #4 is lean. #5 could possibly be rings, valve stem seals or? Maybe the coil isn't firing there?

So then I did a leak down test. #1 was 20%. #2 was 10%. #3-6 I couldn't get much of a reading at all. Confused, I went back to #1 and nothing again. By nothing, I mean no pressure could build up - and yes, the valves were closed. #4 I couldn't tell where the air was going, but the others it was obvious it was leaking past the rings.

So today I pulled the injectors, because I am going to swap #4 and #1 to see if the lean condition follows or? I'm also going to swap 5 and 6 with 2 and 3. To see if those conditions change as well. While doing this, I did a compression test. #1 150, #2 130, #3, 210, #4 60, #5 80, #6 95. Then I went back to #1 and checked it again for 65.

So what I'm finding is sometimes I have good compression with no leakdown, and other times it's very low with lots of leaking. Tomorrow? I'll squirt some oil in the cylinders and see if that makes a difference. If not, I'll be pulling the valve cover and looking there before pulling the head.

So now question....
If I find I need engine work, I was thinking about scrapping it and swapping in a SBC. For those that have done the swap, would it be the cheaper way to go? or should I spend the $'s and fix my 4.0l for now. Money is tight with xmas coming up....


Also, I got to thinking today, the dang thing might still be under the extended warranty that I bought. So Monday I'll call the dealership and see if they can tell me if it is. $100 deductable is nothing for a new motor

 

[Kiel]

Also, I got to thinking today, the dang thing might still be under the extended warranty that I bought. So Monday I'll call the dealership and see if they can tell me if it is. $100 deductable is nothing for a new motor [/QUOTE]

Somehow I think they are gonna flag your claim when they see it

 

[Tacoma]

I would probably never spend money on a 4.0. For one, Cody says they suck, and he's right. For two, you can get running 350's for less than doing nearly anything to a 4.0.

Meh. Crapshoot. Do you have GM-compatible trannies laying around? You can get an adapter plate from Jeg's or Summit for like 80 beans, but I can't remember a damn thing about later Jeep stuff.

 

[waynehartwig]

Problem with the swap is I would need to get everything out of a 04 or newer - requirement of the swap and still be emissions legal.

Without making any calls, etc. I bet motor, accessories, harness and computer are at least $2k. Then I'd need radiator, motor mounts, etc. I believe my NV3550 will bolt up to a SBC? I've thought about just doing a 4.3 (V6) swap??

 

[Tacoma]

oh, yeah, I forgot you've got a new Jeep.

In that case, the 4.0 is probably cheaper.

I really wonder what's up with your valvetrain. Keep us apprised, I'm so very curious now.

 

[waynehartwig]

Also, I got to thinking today, the dang thing might still be under the extended warranty that I bought. So Monday I'll call the dealership and see if they can tell me if it is. $100 deductable is nothing for a new motor

Somehow I think they are gonna flag your claim when they see it[/QUOTE]

Why's that? It's not a broken u joint. The motor has never been overheated. It's always ran warm, since day one, but now it's running warmer than before. But how would 39's cause a motor to loose compression and run warm?

 

[waynehartwig]

oh, yeah, I forgot you've got a new Jeep.

In that case, the 4.0 is probably cheaper.

I really wonder what's up with your valvetrain. Keep us apprised, I'm so very curious now.

Will do!

 

[Bart]

I've been contemplating the SBC route myself, and that's one reason I kept it a 97 over the 99 I could have used. Let me know what you figure out. My feelings on a 4.3 vs V8 is you're doing the work anyway, why not get the extra power.

 

[waynehartwig]

I've been contemplating the SBC route myself, and that's one reason I kept it a 97 over the 99 I could have used. Let me know what you figure out. My feelings on a 4.3 vs V8 is you're doing the work anyway, why not get the extra power.

I was thinking the same thing, but I could probably find a 4.3 for less? I haven't researched eithers cost, so I don't know for sure.

I haven't retested the motor yet with wet rings to see if it makes any difference before I pull the head off. Squirtin oil in the holes might tell me if the problem is in the head/gasket or if the rings are shot. No matter what, at this point the head has to come off. Adding the oil might tell me if the block has to come out or not, too.

Before I get that far into it though, I need to put it back together so I can drive it into the garage and work on it there where it's flat. I'll just need to flatten the tires to get it in the garage, and then put it on stands. I'll never get the motor out on a 30* sloped driveway! Plus the weather is starting to get crappy and cold. In the garage I can have the heater on and be out of the rain/snow/etc.

But I've got 3 customers axles here right now that I have to do something with first....

 

[78mitsu]

wayne,

did you do a compression test/cylinder balance test? (all the plugs out) a leakdown test is cool, but a compression test will tell you more. Also, vacuum test data could be really helpful, do you get a mil? so with your plug description, My guess is a leak on your intake manifold gasket, or maybe an exhaust seat thats bogus, or a bent valve/valves.

on the chevy mill, I don't really think a 4.3 vortec is worth the hastle to swap 6 for 6. if you're going through the effort go LS1.

 

[venpick]

4.3l 2004 chevy silverado engine 875$ with 41k miles
http://www.alltruckinc.com/ 3380s 500 w
i got my 5.7 vortec from these quys for $1350 and it came with everything i wanted. ecm, wireharness, headers, air intake, fuel lines , all the front accessorys like ac, alternator, etc etc steve at the front desk made sure i got everything that i needed. i also got to see the motor run in the crashed up vehicle before i bought it.

http://search2527.used-auto-parts.biz/cgi-bin/search.cgi

this page shows only one 2004 chevy sivlerado but i did not search any other vehicle year or types. Im not sure what vehicles the motors came in but you can use their search to look for others if you now which ones.

 

[Kiel]

Somehow I think they are gonna flag your claim when they see it

Why's that? It's not a broken u joint. The motor has never been overheated. It's always ran warm, since day one, but now it's running warmer than before. But how would 39's cause a motor to loose compression and run warm?[/QUOTE]

You know the dealer, try explaining it to them that way. I'm sure they will warranty it Dealers are gonna void your warranty if you have an aftermarket gas cap on that thing

 

[waynehartwig]

wayne,

did you do a compression test/cylinder balance test? (all the plugs out) a leakdown test is cool, but a compression test will tell you more. Also, vacuum test data could be really helpful, do you get a mil? so with your plug description, My guess is a leak on your intake manifold gasket, or maybe an exhaust seat thats bogus, or a bent valve/valves.

on the chevy mill, I don't really think a 4.3 vortec is worth the hastle to swap 6 for 6. if you're going through the effort go LS1.

I did, guess I didn't post the results? The motor hasn't be ran since the PNW Jeep thing about a month ago and I did the test this last weekend...
1 - 130
2 - 125
3 - 210
4 - 65
5 - 85
6 - 120
...These are off memory. But it looks like I have something going on between 4 and 5. Jeep 0331 heads are known to crack between 3 and 4. When doing a leakdown on 4, I could not tell where the air was going. All of the others I could. Also the numbers change leading me to believe I may have something going on with valves or? Bottom line, the head has to come off.

Maybe I'll go out right now and squirt each cylinder with oil to see if the numbers change. I've been busy with other stuff and I still need to call Jeep and see if the warrranty is still valid on this thing, too.

4.3 has more power than the Jeep 4.0l It's also a much more efficent motor and even though it's a V6, it can be easily made to put out the same HP that a 350 does without compromising reliabilty.

 

[waynehartwig]

Why's that? It's not a broken u joint. The motor has never been overheated. It's always ran warm, since day one, but now it's running warmer than before. But how would 39's cause a motor to loose compression and run warm?

You know the dealer, try explaining it to them that way. I'm sure they will warranty it Dealers are gonna void your warranty if you have an aftermarket gas cap on that thing[/QUOTE]

Yeah, and I'll fight them for it, too. My Rubicon was about 6 months old when a steering u joint failed and took out both shafts. At first the dealer saw my rig, and immediately said I'm not touching it and walked off. Then out comes the service manager saying no way. I gave my little speach and they fixed it under warranty. Replaced the entire drivers? side assembly.

We have a right to modify our vehicles. It's up to THEM to PROVE it was this modification that hurt the part in question. We don't have to prove anything and the courts will not require us to prove anything. It's all on them and they know it...

 

[Kiel]

How are you gonna make the 4.3 have as much power as a 350? Sounds like a waste of money, when you could pretty much spend the same amount and get a 5.3 or whatever. Plus you could do the same stuff to the v8 and blow away the 4.3

 

[78mitsu]

I did, guess I didn't post the results? The motor hasn't be ran since the PNW Jeep thing about a month ago and I did the test this last weekend...
1 - 130
2 - 125
3 - 210
4 - 65
5 - 85
6 - 120
...These are off memory. But it looks like I have something going on between 4 and 5. Jeep 0331 heads are known to crack between 3 and 4. When doing a leakdown on 4, I could not tell where the air was going. All of the others I could. Also the numbers change leading me to believe I may have something going on with valves or? Bottom line, the head has to come off.

Maybe I'll go out right now and squirt each cylinder with oil to see if the numbers change. I've been busy with other stuff and I still need to call Jeep and see if the warrranty is still valid on this thing, too.

4.3 has more power than the Jeep 4.0l It's also a much more efficent motor and even though it's a V6, it can be easily made to put out the same HP that a 350 does without compromising reliabilty.

have you thought about maybe warn cam or bent pushrods? or broken valve-springs?

 

[78mitsu]

I've got a 4.3 vortec, they make good torque and good power, but nothing like my 350. A 350 done right to a 4.3 done right you're still missing 1/4 of the displacement, a red lable 5.3 makes 320 hp and the 6.0 properly tuned can make 450hp, so I agree it would make enough power to pull around your jeep, pound for pound I think you'd be better off with a ls1-6. But if you can fix it for $300 with a valvejob and a head gasket, doesn't that make better sense?

 

[Kiel]

I say turbocharge the bad motor and it will make up for the 2 bad cylinders and put you back to stock 4.0 levels again

 

[waynehartwig]

I've got a 4.3 vortec, they make good torque and good power, but nothing like my 350. A 350 done right to a 4.3 done right you're still missing 1/4 of the displacement, a red lable 5.3 makes 320 hp and the 6.0 properly tuned can make 450hp, so I agree it would make enough power to pull around your jeep, pound for pound I think you'd be better off with a ls1-6. But if you can fix it for $300 with a valvejob and a head gasket, doesn't that make better sense?

I'm not talking about 'buildt' engines. Buildt there is no way a 4.3 can come anywhere near a 350. Just talking stock is all... I can easily build a 350 to put out BBC numbers, but this is for a 5k lb Jeep, not Camaro. It'l never see the high rpm numbers. As it is, this motor has probably only ever seen 3500 tops. 3500 is nothing for a SBC and at that, it's just barely getting ready to make HP.

That does make better sense. If it's an easy fix like that then it will get fixed. But if it's a rebuild, it's not getting fixed.

I ran my compression test with oil in the cylinders. Nothing dramatic, but the numbers are more consistent.
90
70
60
70
70
90
I'm glad to see none of them improve from the oil. That most likely means rings are good. So I'll put it back together and pull it into the garage where I'll take the head off and see what is going on.

 

[waynehartwig]

I say turbocharge the bad motor and it will make up for the 2 bad cylinders and put you back to stock 4.0 levels again