Replace or Rebuild

[Burbanaz]

Ok im not sure which direction i really want to go with my engine. I want to stick with the 6.5 but i dont know if i want to try and rebuild the engine i have now or replace it with a military take out. I have a 94 k2500 suburban so im not sure which block id be starting with or if its even a block worth trying to rebuild. It runs fine but its feels low on power, starts to overheat during hill climbs, and i have to add coolant every 100 miles or so. Plus little the little leaks here and there that just come with age. So i know at minimum i have to replace the head gaskets.

The engine has 205k on it, so if im going to go through the work of replacing the head gaskets im going to pull the whole engine, replace head gaskets, freeze plugs (because i have one that was leaking), injection pump (getting codes 35, 36), glow plugs, injectors. Not sure if i should re ring it or not. Should i just do the headgaskets and the minimum amount of stuff or replace everything i can while i have the engine out?

We go on long offroading trips into the middle or nowhere and i need it to be as reliable as i can get it.

So basically im trying to decide if im going to tear this engine completely down and rebuild the whole thing and try to make it as strong and reliable as possible, or replace it will a military take out. What do u guys think? which would make the most sense money wise? and can i even make my engine more reliable or is it just a problem waiting to happen?

Heres a pic of my truck just because lol

 

[Big T]

Ok im not sure which direction i really want to go with my engine. I want to stick with the 6.5 but i dont know if i want to try and rebuild the engine i have now or replace it with a military take out. I have a 94 k2500 suburban so im not sure which block id be starting with or if its even a block worth trying to rebuild. It runs fine but its feels low on power, starts to overheat during hill climbs, and i have to add coolant every 100 miles or so. Plus little the little leaks here and there that just come with age. So i know at minimum i have to replace the head gaskets.

The engine has 205k on it, so if im going to go through the work of replacing the head gaskets im going to pull the whole engine, replace head gaskets, freeze plugs (because i have one that was leaking), injection pump (getting codes 35, 36), glow plugs, injectors. Not sure if i should re ring it or not. Should i just do the headgaskets and the minimum amount of stuff or replace everything i can while i have the engine out?

We go on long offroading trips into the middle or nowhere and i need it to be as reliable as i can get it.

So basically im trying to decide if im going to tear this engine completely down and rebuild the whole thing and try to make it as strong and reliable as possible, or replace it will a military take out. What do u guys think? which would make the most sense money wise? and can i even make my engine more reliable or is it just a problem waiting to happen?

Heres a pic of my truck just because lol

Nice truck. The wife and I love to take my '99 offroad.

You've got a lengthy list of "issues" so it's hard to zero in on a complete solution. Right off the bat you have an aftermarket front bumper designed for mounting that winch, but there are no snorkel holes or cut outs for air flow through that bumper. You've lost some cooling effect with that bumper/winch in place.

Basic questions:
1. Is the engine stock?
2. Has the cooling system been upgraded/modified?
3. Has that injection pump been replaced?
4. Have the injectors ever been replaced?
5. Does it have blowby coming out the oil fill? Dipstick? Steady stream or puffs?
6. Is there coolant in your engine oil, or oil in your coolant?
7. Original oil lines?
8. Has the radiator ever been pulled and thoroughly cleaned?

 

[ak diesel driver]

you won't know if you want to rebuild yours until you pull the pan and check for cracks

 

[Burbanaz]

Nice truck. The wife and I love to take my '99 offroad.

You've got a lengthy list of "issues" so it's hard to zero in on a complete solution. Right off the bat you have an aftermarket front bumper designed for mounting that winch, but there are no snorkel holes or cut outs for air flow through that bumper. You've lost some cooling effect with that bumper/winch in place.

Basic questions:
1. Is the engine stock?
2. Has the cooling system been upgraded/modified?
3. Has that injection pump been replaced?
4. Have the injectors ever been replaced?
5. Does it have blowby coming out the oil fill? Dipstick? Steady stream or puffs?
6. Is there coolant in your engine oil, or oil in your coolant?
7. Original oil lines?
8. Has the radiator ever been pulled and thoroughly cleaned?

Yea i built the bumper for my last suburban which was a gas 454 so i didnt have any cooling issues but im going to rebuild it and put winch inside and add vents to help with cooling. The truck is stock though engine and cooling system wise, i dont think the injection pump or injectors have been replaced. There isnt coolant in my oil or oil in my coolant i just lose it over a little at a time. Original oil cooler lines.

Thanks ak diesel driver, i guess ill just pull it them and get it on a stand and pull the pan and check for cracks, am i mainly looking for them at the mains?

I just dont want to sink a bunch of money and time into rebuilding this engine if its not worth it

 

[ak diesel driver]

look at where the main bearing cap bolts enter the block, if it's cracked you'll see it down the sides. don't even have to pull the caps

 

[Burbanaz]

look at where the main bearing cap bolts enter the block, if it's cracked you'll see it down the sides. don't even have to pull the caps

OK thanks I'll pull the engine then and the first thing I'll check is if its cracking there. Is it gong to be easier to pull the engine and tranny both together or unbolt them and just pull the engine and leave the tranny in the truck?

The way I see it hopefully the are no cracks and I'll n just do head gaskets, head studs, glow plugs and injectors, etc.

Thanks for answering all my questions guys I'm just trying to get as much info as I can before I start

Anything else u guys think is with changing our replacing since I'll have the engine out for overall reliability? Think I should re ring it?

 

[ak diesel driver]

you never did mention how much blowby you have. if it's got any at all I'd re ring it

 

[Will L.]

I like the rig.
New freeze plugs, all new bearings, new timing chain/gears, front & rear main seals. Check the valve guides and seats. New rocker arm buttons. How old is the water pump and harmonic balancer?
If you do go with new rings, check out gapless rings. More expensive but longer life and they handle heat distortion better.
Melling is the only mfr that makes the oil pump, all the others you see are melling relabled. Just get the one with the higher volume - for all squirter blocks. Have fun.

 

[Burbanaz]

I do have some blow by when its warm at idle, if i take off the oil filler cap i can see it. If i re ring it do i need to get the cylinders bored?

Im guessing the water pump and balancer are as old as the truck so im going to replace those while its out also. I dont think i have a squiter block since im a 94.. Ill look into the gapless rings, ive heard people using them on race engines but havent heart much about them long term.

The nice thing is the trip we got back from is the last one we have planned till next year and we have 2 other cars and another 4x4 truck so i can tear it apart and take my time getting the right parts and building it back up properly.

 

[WarWagon]

Lots of places to loose water. Most overlooked is the radiator including the trans oil cooler leaking into the transmission. Cooling fan tends to evaporate the coolant from radiator leaks. Best to know where the leak is before major work. IMO you may not need to overhaul the engine. Head gaskets are good for around 200K so you are there...

Check everywhere for cracks including cyl head bolt holes. To check the mains leave the engine turned over on the stand. Clean around the main webs. Any cracks will appear as engine oil drains out and leaves black lines overnight. You should mag the rest of the block if the overnight test passes.

I would replace the heads outright. Valves and seats wear, heads crack...

You just need to deglaze the cylinders. This is not like a gas engine where the cylinders taper wear so badly. Then I would put gapless rings in it to keep the soot out of the oil. It is amazing how much cleaner my oil is with the gapless rings. Although it gets black, you can still see through it and read the marks on the dipstick after 2K miles on the oil.
http://www.thetruckstop.us/forum/showthread.php?29135-Total-Seal-Gapless-rings

Oil pump, timing chain, head studs with locktight in the block side of them, bearings, gaskets, heads, possible manifolds from warping, injectors, glow plugs, gapless rings.

Improvements:
HO water pump from 1998
Low temp fan clutch or new 1998 fan clutch
Duramax or 9 blade cooling fan.
Walbro lift pump with tank sock removal.
Lift pump relay mod.
CAT water separator prefilter.

 

[Burbanaz]

the main thing is if im going to do the work i want it to be reliable, if i cant make my current engine reliable for less than like a teds take out then i dont see why i would even bother with mine instead of just replacing it.

 

[WarWagon]

the main thing is if im going to do the work i want it to be reliable, if i cant make my current engine reliable for less than like a teds take out then i dont see why i would even bother with mine instead of just replacing it.

A take out engine will still need a ring job for the best results. Again tracking down the leak will determine what you need to do. Yanking a running engine with good oil samples is not going to help reliability. Then you loose the transmission in the sticks anyway...

 

[Burbanaz]

from what ive been able to tell so far it seems that its my head gasket or gaskets, so at a very minimum im going to need to do that. Then i figured since i needed to do that and the mileage is high i should do a few other things to help reliability later. It runs great but is starting to overheat not on hills.

I havent checked the oil for coolant though, is that what ur talking about with the oil samples?

 

[Big T]

Guys here recommend testing the head gaskets by pulling the serp belt and then the T-stat cover and watching the coolant in there while running the engine (birefly) to see if there are any bubbles in the coolant and from which side (cylinder bank) they're coming from.

It seems like you're chomping at the bit to roll up the sleeves and get into an engine freshening project. I admire that, but you may not have to go there.

BTW, my son's '94:

 

[WarWagon]

Both for seeing if you are getting coolant and general engine condition. If the engine is in good shape it is a waste to yank it out for a rebuild. The heads are known to crack so you could have either issue. Pull the coolant t-stat crossover, drop the belt, start the engine and see what side the bubbles are coming from.

Once you pull the engine out and find cracks it becomes junk. Very few will drop it back in. Not knowing is a reliability question. How long they run with known cracks is an experiment I am currently running.

 

[Big T]

Both for seeing if you are getting coolant and general engine condition. If the engine is in good shape it is a waste to yank it out for a rebuild. The heads are known to crack so you could have either issue. Pull the coolant t-stat crossover, drop the belt, start the engine and see what side the bubbles are coming from.

Once you pull the engine out and find cracks it becomes junk. Very few will drop it back in. Not knowing is a reliability question. How long they run with known cracks is an experiment I am currently running.

Is there an over/under line on the miles for when it gives out?:agreed::hihi:

 

[Burbanaz]

Guys here recommend testing the head gaskets by pulling the serp belt and then the T-stat cover and watching the coolant in there while running the engine (birefly) to see if there are any bubbles in the coolant and from which side (cylinder bank) they're coming from.

It seems like you're chomping at the bit to roll up the sleeves and get into an engine freshening project. I admire that, but you may not have to go there.

BTW, my son's '94:

Thats a nice suburban lol looks like exactly like mine pretty much. I really dont want to pull the engine and replace everything lol i just want reliability and im tired of going on trips and worrying its not going to make it or that its going to overheat. Ill pull the tstat housing and see if i can see where the bubbles are coming from, and maybe have somewhere check the oil for coolant.

I just want to get started on whatever is going to give me a good reliable engine lol, im not super patient so whatever i decide i just want to start on.

Both for seeing if you are getting coolant and general engine condition. If the engine is in good shape it is a waste to yank it out for a rebuild. The heads are known to crack so you could have either issue. Pull the coolant t-stat crossover, drop the belt, start the engine and see what side the bubbles are coming from.

Once you pull the engine out and find cracks it becomes junk. Very few will drop it back in. Not knowing is a reliability question. How long they run with known cracks is an experiment I am currently running.

Yea i agree, if i pulled it and found cracks i wouldnt put it back in probably. It runs well, i just worry about it when were on trips. Ill check and find out best i can if its the head gaskets this week so i can figure out what i need to get started on.

 

[WarWagon]

Is there an over/under line on the miles for when it gives out?:agreed::hihi:

We will see when the crank impacts the pavement...

If you need peace of mind get AAA or another 6.5 to tow your broken down 6.5. Many threads on here on how to overcome known weaknesses on these trucks. Mainly PMD's followed by cooling system upgrades.