So I'm considering tackling a blown head gasket repair. 2002 Disco with 200K miles and SAI. My first question is should I purchase already rebuilt cylinder heads? Anyone have any idea how many hours this will take me? Current advice as to a Cylinder Head Gasket Set that anyone has used would be great as well.
Rebuild Cylinder Heads
- Thread starter wrldky
- Start date
Purchasing rebuilt cylinder heads is one option and the main advantage is that it shortens the time needed to do the job. Iif you send your existing heads to a machine shop for milling and valve job that could take a few days depending on the shop's schedule, how far it is from you, etc.
If you buy rebuilt heads it will probably be more expensive and then you'll have a second set of heads (unless you buy the new ones from a place that requires a core). If you absolutely have to get your truck back on the road and can't wait a few days then buy the rebuilt heads. If you have the time and access to a machine shop within a convenient distance, get the job done locally. Then you can at least go talk to someone if they screw anything up and you could save some money for other important parts of the job, like beer.
I had great results with the cylinder head gasket kit that I bought from Will Tillery, a vendor who frequents this site and is based in VA. Kits are available from other vendors here, like PT Schram, or the larger national dealers like Rovers North, Lucky 8, Atlantic British and so on. Buy the complete kit, don't try to piece it together yourself. Expect to pay somewhere in the range of $180 - $220 for the complete kit. Use brand new stretch bolts for the reassembly unless you enjoy taking your engine apart to repeat the job soon. Will's kit came with Elring composite gaskets, which came highly recommended to me. Others are available, people may have their preferences, I took trusted advice on the Elrings and they did not disappoint.
Here is a write-up I did of my experience with the head gasket job a few years ago. Hope you find it helpful. It took me about 32 hours over the course of a week, and I went very slowly. The repair lasted over 50,000 miles (at which point I sold the truck) and as far as I know is still holding up.
If you buy rebuilt heads it will probably be more expensive and then you'll have a second set of heads (unless you buy the new ones from a place that requires a core). If you absolutely have to get your truck back on the road and can't wait a few days then buy the rebuilt heads. If you have the time and access to a machine shop within a convenient distance, get the job done locally. Then you can at least go talk to someone if they screw anything up and you could save some money for other important parts of the job, like beer.
I had great results with the cylinder head gasket kit that I bought from Will Tillery, a vendor who frequents this site and is based in VA. Kits are available from other vendors here, like PT Schram, or the larger national dealers like Rovers North, Lucky 8, Atlantic British and so on. Buy the complete kit, don't try to piece it together yourself. Expect to pay somewhere in the range of $180 - $220 for the complete kit. Use brand new stretch bolts for the reassembly unless you enjoy taking your engine apart to repeat the job soon. Will's kit came with Elring composite gaskets, which came highly recommended to me. Others are available, people may have their preferences, I took trusted advice on the Elrings and they did not disappoint.
Here is a write-up I did of my experience with the head gasket job a few years ago. Hope you find it helpful. It took me about 32 hours over the course of a week, and I went very slowly. The repair lasted over 50,000 miles (at which point I sold the truck) and as far as I know is still holding up.
I also got my parts from Will, did mine about 4 years ago. In your case, with 200,000 miles on the engine you really need to consider new cam, lifters, rocker arm assemblies, timing chain, oil pump, water pump, coil packs and ignition wires. The R&R of the heads is a pretty big job, especially with SAI and it being your first time. With the heads off you have easy access to many things that are going to be inaccessible or very difficult to access once they are back on, namely everything behind the timing cover.
This is an important point. It would be futile to go to all the trouble of replacing your head gaskets if you don't address the causes of failure in the first place and don't take extra steps to prevent it happening again in the next 70,000 miles. Head gasket failure is often a symptom of a problem elsewhere in the cooling system. You engine overheated for some reason - not because the head gaskets failed. If you want to extend the life of your engine in a meaningful way you need to address 2 issues:
1. What actually caused the head gaskets to fail?
2. What are the vulnerabilities in your cooling system you should address while you're replacing the head gaskets?
As to #1, say your 16-year old radiator is partially clogged. Replacing the head gaskets will not fix that cause of overheating. You will also need to replace the radiator.
As to #2, kcabpilot is spot on. Identify places where your cooling system could fail and replace those components. Water pump, thermostat, fan clutch, and hoses will add a couple hundred dollars to your project budget but will be well worth the investment for the peace of mind you get. Nothing will bum you out after completing your head gasket job like needing to do it again in 6 months because your factory water pump gave up.
At a certain point you need to decide how much longer you want to keep the truck and what you're willing to invest to make it run well. It may make more sense to buy a used engine with lower miles, rebuild it (like kcabpilot suggests) while it's outside the vehicle, then do an engine swap. If you are going to try to extend the life of a 200k engine you probably will need to do more than just rebuild the top end.
Thank you Tugela and Kcabpilot! It's my son's truck and I'm not sure I need 200K miles. 50K would be nice though. My son and I have replaced the timing chain, oil pump, water pump, coil packs and ignition wires. I have use Will Tillery a lot in the past and he has been great. Plus he is close so I typically get parts the next day. I was curious about the cam shaft. If i replace that I might as well replace the radiator. I'm fairly handy and I have a decent set of garage tools but I am weary of pulling the engine. I understand I can pull the cam shaft with removing the engine. advice on whether or not to do the cam?
Regarding the cam/lifter/rocker/timing chaing/oil pump question:
Honestly, it depends upon how long you plan to keep the truck. Sorry to say, but a 2002 with 200k+ miles is not the most desirable Discovery out there. I don't think you can plan to get much money back on that investment if you're going to sell it in a year.
However, if you really like the truck and you're in for the long haul, it's probably wise to refresh your tired engine while it's already apart.
In all likelihood, your cam is worn, your timing chain is sloppy as hell, and your valvetrain is worn and noisy. If it was mine, I'd be pulling and evaluating these parts before replacing as necessary. But that's because I only keep vehicles for 1-2 years, so longevity is not a significant concern. I'd probably let the cam condition dictate additional work on the valvetrain. Measure the lobes through the valley while the intake is out, no need to remove unless it's worn. "While you're in there" work is a good thing to think about, but you should consider the return on your investment as well, since this side-work can triple your costs, or worse.
Honestly, it depends upon how long you plan to keep the truck. Sorry to say, but a 2002 with 200k+ miles is not the most desirable Discovery out there. I don't think you can plan to get much money back on that investment if you're going to sell it in a year.
However, if you really like the truck and you're in for the long haul, it's probably wise to refresh your tired engine while it's already apart.
In all likelihood, your cam is worn, your timing chain is sloppy as hell, and your valvetrain is worn and noisy. If it was mine, I'd be pulling and evaluating these parts before replacing as necessary. But that's because I only keep vehicles for 1-2 years, so longevity is not a significant concern. I'd probably let the cam condition dictate additional work on the valvetrain. Measure the lobes through the valley while the intake is out, no need to remove unless it's worn. "While you're in there" work is a good thing to think about, but you should consider the return on your investment as well, since this side-work can triple your costs, or worse.
In my experience, there does not have to be a cause or reason for head gaskets to fail. They just fail.
Hard to believe that a D2 with 200K hasn't already had the thing torn apart many times. I'd just do the heads and go with it. Mine with 220K has probably been apart once for cam and second for head gaskets. Since I bought it with 97K on it I'm sure the heads were done once before I had it. Mine currently is leaking from the front of the head again and I just don't care.
Regarding camshaft replacement, there was a thread titled "New Cam with Head Gasket Change?" posted awhile back. I made a long post in that thread about things to consider. If you decide to install a new cam, give it a quick read. A new cam is great, but there is the possibility to cause more harm than good if it isn't done properly.
Thanks guys. I have been in touch with Will Tillery and he is sending me everything I need with reconditioned heads. Once I have the heads off should I have the truck towed to a shop and have them pressure test the engine block? There was a lower engine knock that i don't think rebuilding the upper end is going to help. Also there is a place near hear that cleans fuel injectors. Should I have that done as well?
Pressure testing the engine block won't solve your lower engine knock issue.
Take the pan off and inspect at least rod bearings, it is a dirty job but easy. If you come across a scored or discolored journal, pull the engine.
Take the pan off and inspect at least rod bearings, it is a dirty job but easy. If you come across a scored or discolored journal, pull the engine.
This begs the question: what led you to the conclusion that you have a "blown" head gasket to begin with?
Kcabpilot, that is a great question. It had all the symptoms of a head gasket. Coolant bubbling when you took the cap off, white smoke, throwing codes, loud banging from the top of the engine. But then again it could very well not. I guess I will find out soon enough. Ihave the valley pan gasket off. Is it normal for some of the lifters tonot be all the way seated? i can include a picture.
The lifters will appear to be at different heights, as they are each at different points along camshaft lobes. Also, if the engine has sat for a while, the plunger inside the hydraulic lifter can "bleed down."
If there was banging from the bottom-end, I would pull rod caps and take a look at the bearings. You should use new connecting rod bolts when putting the caps back on and follow the RAVE manual instructions for torquing, then angle torquing these bolts. The bolts are only a few dollars each. I didn't know new bolts were necessary the first time I was rebuilding my 4.0 and had one bolt snap while torquing it. Out they all came and new ones were in the mail the next day.
If there was banging from the bottom-end, I would pull rod caps and take a look at the bearings. You should use new connecting rod bolts when putting the caps back on and follow the RAVE manual instructions for torquing, then angle torquing these bolts. The bolts are only a few dollars each. I didn't know new bolts were necessary the first time I was rebuilding my 4.0 and had one bolt snap while torquing it. Out they all came and new ones were in the mail the next day.
I think if your bottom end is knocking you should pull the engine anyway.
A head job, while making you feel good and relieving stress, won't do anything to get rid of a bottom end knock.
The worst part of rebuilding an engine is pulling it out. The rebuild itself is not bad at all.
A head job, while making you feel good and relieving stress, won't do anything to get rid of a bottom end knock.
The worst part of rebuilding an engine is pulling it out. The rebuild itself is not bad at all.
Lots of good advice. Right now time and money are my biggest concerns. It's my son;s truck and he is leaving for college in August so i just need to get a good year out of it, Longer would be nicer but college payments are my biggest concern now. I am enjoying doing this project with him though. So I'm not going to get into the CAM but would like to do the lifters. Advice on new lifters and rods without replacing the cam? I did read your post PhD PolyMath.