Replace the head gaskets or replace the engine?

Well I found out today that my head gasket is indeed leaking. I don't want to say it's blown because it's so minor. I'll post later about how I verified it. It's really pretty cool. So, my 05 V6 has 303k on the clock. And even with the head gasket leaking it runs absolutely perfect. No skips, misfires, surges etc. and the temp gauge never even reaches halfway. Since I replaced the PS pump there's not a leak on it anywhere, (excluding of course the head gasket). So to me I have two choices. I can replace the head gaskets or get a lower mileage engine and put in it. I've pretty much made up my mind to do the head gaskets but I'd like others opinions on it anyway. I know the "best" solution is to replace the engine due to the miles. But I have a reason (other than the cost) to not do that. I want to see how many miles I can put on this thing with the original engine and transmission. One thing that comes into play is the fact that I'm a lifelong auto tech so I will be doing the work myself and I don't expect to spend over $500 even including replacing peripheral stuff like hoses, pcv valve, etc. I will spend whatever's needed once I'm in there but I don't expect more than $500. So if you would share your opinions I'd really appreciate it. Sorry this ran so long. I'll reply to this thread soon to share how I diagnosed this. If I can figure out how I'll even share a pic or video about it. Thanks

 

I’d say, if everything is working as it should and you have the ability to replace the HG then I’d go for it! I recently purchased a 99 limited with leaking coolant, with no experience, I took the heads off to find a crack. I’m proud of myself and happy I did it. I realize I am fortunate to be able to have the financial independence to tinker but, if you can fix your vehicle for under 500 can’t find a reason to argue that!

 

Personally, you have a good sounding rig. I would think a replaced engine MIGHT cause a buyer some concern. Also, replacing the engine, unless new, might open a can of worms. Follow the KISS theory (Keep It Simple, Stupid!) and do the minimal (IF that is truly all it needs!

 

Thanks for the opinions guys. Since I posted I've now decided I'm going to need to replace the timing components as well. I started tearing it down and checked the tensioner and it's pretty far extended meaning it's worn or stretched some. But I've also pulled the valve covers and there's no sludge whatsoever so I'm plowing forward into it. Unless I find something I don't expect I'll continue and repair what I've got.

 

def replace the head gasket. We went through this same process and just did the HG after all. Best decision we could've made, changed all the parts we could while we were at it.

 

New head gaskets, valve seals and refinish the valve seats. Of course, new gaskets on everything.

 

Thanks for the responses guys. I said I would post about how I diagnosed this leak. So, I had tried a combustion gas test and a pressure test and neither showed a head gasket problem. As a final test decided to try one more thing. I got out my borescope and ran it down into the #6 cylinder. Then I compared it to the #4 cylinder. No noticeable difference. So I put the pressure tester on it and pumped it up to 25 psi. As I was looking around inside cylinder #6 I saw a drop of coolant come out between the head and the block and run down the cylinder wall. I was amazed since I'd never done this before. I took a video and a still shot of it with the borescope but unfortunately the type of media is uses can't be uploaded here. If anyone would like to see it, message me and I'll see if I can email it to you. It's really interesting, at least to me. Anyway, I'm about halfway into tearing it down now and I'll post updates as I go along. Not really gonna do a DIY on it but after I'm done I'll gladly help anyone who has any questions about it.

 

We ran into the same issue. Took seven months of back and forth to finally have it fail the normal tests. Our only symptom was coolant overflowing from the reservoir. We ended up doing three sets of pressure tests and a coolant test on the 9th time it finally failed. Zero other symptoms. We scoped the sixth cylinder and checked for cleaning on the inside but that was a no go. Checked everything replaced caps etc to no avail. Had the head gasket replaced and all they found when they did a milling on the head was a tiny slump near six. I mean tiny too. Got it fixed replaced everything we could while we were at it and haven’t had a problem since.

 

Another vote for the head gasket! (me)

Cheers,

Sean

 

Add another vote to replace the HG. Thats awesome you were able to find the leak with some more diagnosis, those combustion gas & pressure testers dont always identify problems. Glad you are able to do the work yourself, head gasket repairs on these engines are not cheap, most places call for like 20+ hours of labor!

Another thing you should check is if you use synthetic oil that might be the problem, I've heard it can cause head gasket issues... might want to get that cheap stuff out of there asap, its super slippery...

 

LMAO. Thanks Yoda
I am at a stopping point now unfortunately. I thought I had a 10mm double hexagon socket for the head bolts but turns out I didn't. And none of the parts stores around here have one. I just ordered two of them on Amazon. Got two just in case I break one. I guess I'll spend the next couple days getting everything cleaned up. And I'll get my parts coming. I hope to finish it by the end of the week.
On another note: If you saw my post a few weeks ago you know about all the maintenance I did. Turns out 90% of what I did then had to be redone during this job. Wish I had known about the head gasket then.

 

Good thing they always run away. Damn 10mm.

 

Thought I'd give a progress update. Everything is apart, the heads are at the machine shop and I'm waiting for parts. Most importantly, at least to me is, my original estimate of $500 is way out the window. As soon as I saw the timing chain tensioner I knew it was gonna get higher. And originally I was gonna just replace the valve seals myself and skip having the heads serviced but I thought better of it. So as of right now I'm expecting to wind up with between $800 and $1000. Would have been even worse if I hadn't just replaced the water pump, radiator hoses, belt, tensioner, and all pulleys about a month ago. Sure would've been nice to know this was coming when I did all that though. Other than the hoses, everything I did then had to come back off now.

 

I'm going to put new plugs in while I've got it apart and was wondering if anyone has switched to platinum or iridium. I've been running the stock Denso copper plugs and looking on Amazon the reviews on iridium are mixed. Some say it runs better while some say otherwise. It would be nice to not have to worry about replacing them for 90K or so miles. Anyone switched and have real world experience to offer? Thanks

 

Update: It's done. Finally got it all back together. Would have been done Thursday but I carelessly broke one of the VVT solenoids. I went ahead and ordered both of them and they arrived today. So far, it's perfect, fingers crossed. It actually sounds better, idles better and has a little better acceleration than before. I attribute that to the fact that the old timing chain was stretched to the point that the cam timing was a whole tooth retarded. Also while it was apart I cleaned out the carbon buildup in the intake runners and on the top of the pistons. The machine shop serviced the heads and cut 4 thousands off of them. So between all of that it does seem a little more peppy. Of course it's hard to tell since I've been driving my 5.7 Tundra while this was out of service. Compared to that it's not so peppy, lol.
Overall thoughts about this job for anyone who's considering doing it themselves: It's a LOT of work. There's no particular part of it that's overly difficult or technical but you can plan on spending a lot of time on it. And there's a lot of stretching to reach things. One thing that helped me was using a lift rather than having to work with a creeper. Plus, I took the front tires off and lowered it till the front rotors almost touched the floor. Even with that it's a reach to get to the stuff at the back. I had one of my students helping me and he climbed under the hood and did a lot of that part for me. I think most people that have some mechanical aptitude and experience should be fine doing this. Just take your time, READ the FSM and expect it to take a little while. If anyone ever needs advice on this, feel free to reach out to me. I'll be glad to share what I know about it.

 

That's awesome! Now it will probably go another 300k!

 

I'm shooting for hitting 500K with it. I'll reassess at that point, lol. I have high hopes it will make it. I saw virtually no sludge or any signs of neglect so I think the previous owners kept up with the oil changes. And now everything is new or like new except the block, crank, rods, and pistons. Here's hoping....