Head gasket repair on 4th gen 4runner V6

Jeremy P.

Adventurer
I have had my 2004 4runner for about 2 1/2 years, and it has always had an ongoing issue of losing coolant since I bought it, primarily by overflowing the coolant expansion tank. I replaced the radiator because it had a tiny leak, changed the radiator cap and checked the thermostat. Still I had the issue of the expansion tank slowly overflowing at higher speeds or while towing a trailer. I did not have any of the typical codes that people see when the head gasket is leaking such as misfires but after reading other peoples symptoms I was quite confident that the head gasket was the issue. It also added a lot of stress to the drive when we went to the Overland Expo East and the Vermont Overland Rally this fall. My theory on what would happen is combustion gases would slowly force coolant out the radiator and until the coolant temp sensor wasn't submerged, then the temp gauge would quickly shoot up, especially when coming to a stop. With higher rpm (~2500) the temp would drop right back down because the water pump was able to move enough volume to cover the sensor. When just driving around town, I could go for weeks with no problem probably because there wasn't enough cylinder pressure to force coolant out.

I decided to finally take care of the issue before winter. I used service manual documents from here: http://www.toyota-4runner.org/4th-gen-t4rs/100275-service-manual-download-links.html
I used the 2006 version of the manual. I compared some sections to the 2003 version and they were almost identical but the 2006 seemed to have some improvements in some of the reassembly steps. It can be a hassle to find all the steps because it isn't covered in one section, you have to jump around a bit.

I ordered a valve grind gasket set, 04112-31720, which doesn't have quite everything that a master set has but had all the gaskets needed to replace the head gaskets and was a bit cheaper.
I also ordered a set of 16 head bolts, 90910-02162, even though the originals can possibly be reused if they measure in spec according to the manual. I just didn't want to have to worry about it.
The head bolts need a 12 point double hex socket. I ordered CTA tools 9295, which is a pair of toyota head bolt sockets. The larger one fits the 4.0 V6 head bolts.
I also replaced the water pump with aisin WPT802 which is supposed to be the same as OEM. It actually had a milled spot where 'toyota' is cast in on the OEM pump, so I suspect they mill 'toyota' off when these are not being sold as a toyota branded part.
I ended up replacing the exhaust manifold studs because the originals where so rusted up. I used this set and they fit just right: http://www.ebay.com/itm/231720176295?ru=http%3A%2F%2Fwww.ebay.com%2Fsch%2Fi.html%3F_from%3DR40%26_sacat%3D0%26_nkw%3D231720176295%26_rdc%3D1
I also replaced the thermostat with OEM just to be safe.

The teardown took quite a while because I was dealing with some rusty fasteners. The exhaust manifolds actually had to come out with the heads.
2015-10-26 22.27.35.jpg

Not much is left of the engine after the required parts come off:
2015-10-26 17.22.24.jpg

Keep everything orderly and labeled, especially the valve train parts:
2015-10-26 17.22.51.jpg
 

toyotech

Expedition Leader
When putting fipg on the timing change cover. Make sure you don't glob it everywhere on the cover. For the instructions on where to apply it. Otherwise you may plug up oil passages.

Mostly blown HG right where those tiny holes are in between the cylinders.


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Jeremy P.

Adventurer
The gaskets and heads had a small pitted spot between cylinders #4 and #6. The guy at the machine shop confirmed that it is typical from a slowly leaking head gasket.
2015-11-04 10.38.25.jpg

I had a machine shop mill the heads, check the valves, and replace the valve seals that came in the gasket set. I also had them clean up the valve covers and front timing cover. The parts looked so much better after they cleaned them up.
2015-10-31 15.48.41.jpg

I also had the injectors cleaned while they were out. I don't know if it was related to the head gasket but the #6 injector (the typical cylinder to develop a HG leak) is the only one that looked dirty.

The bottom of the #6 injector:
2015-10-27 13.29.07.jpg

The others looked like this:
2015-10-27 13.29.30.jpg

I was worried at first about getting the cams and timing chains all put back together correctly, but the service manual does a good job of describing how to position everything so it goes together correctly. The timing chains have paint marks that line up with the marks on the gears. In this picture you can also see the milled spot on the water pump. I used permatex ultra copper rtv instead of the toyota seal packing and it worked just fine.
2015-11-02 17.35.15.jpg

I decided to use Zerex Asian vehicle antifreeze as it is the same type of antifreeze as oem (even looks exactly the same as the super long life coolant) but is a bit cheaper and easier to find. It was extremely satisfying to have the engine start right up after getting it back together. So far it has been operating as normal after a few weeks and some highway miles. Let me know if you have any questions if you're looking at doing this yourself!
 

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Jeremy P.

Adventurer
When putting fipg on the timing change cover. Make sure you don't glob it everywhere on the cover. For the instructions on where to apply it. Otherwise you may plug up oil passages.
Yeah, the service manual is pretty specific on where and how much sealant to apply. I tried to do it just like it showed. Especially the spot next to the main oil passage from the oil pump. I also didn't pull the oil pan off but used some grease to keep the o-ring in the bottom of the front cover when I slid it on.
 

toyotech

Expedition Leader
Yeah, the service manual is pretty specific on where and how much sealant to apply. I tried to do it just like it showed. Especially the spot next to the main oil passage from the oil pump. I also didn't pull the oil pan off but used some grease to keep the o-ring in the bottom of the front cover when I slid it on.
Yea. Techs usually don't pull the pan. I done it without pulling pan and haven't had an issue. The small leak is very common usually around 150k. Those tiny holes isn't a good idea. Not much gasket material between the cylinders.


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Jeremy P.

Adventurer
I read several threads on other forums about it and figured I could manage it. I have done a timing belt before on a 30 valve v6 and other engine and drivetrain work, so I felt okay taking this on. The rusted bolts, tight crank bolt and difficult to access rear water bypass joint were probably the worst parts. I got the crank bolt loose by wedging a 1/4 x 1" piece of aluminum flat bar through one of the harmonic balancer slots so it prevented the crank from turning and did the same to torque it again.

The head gaskets were apparently updated and so hopefully this was just a one time issue. Here is a good list of 4.0 head gasket related information: http://www.toyota-4runner.org/4th-gen-t4rs/188699-***-v6-head-gasket-action-request-***-5.html
 

toyotech

Expedition Leader
did u have to remove oil pan or front diff? how many miles on yours?
You are suppose to but you can get away without dropping the pan. Just make sure you clean and use enough fipg


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emtmark

Austere Medical Provider
You will be faster the next time around they are sort of known for them


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jbriggsnh

New member
That was a great tutorial Jeremy. I am starting the same next week on a 2004 4R.

1 - Did you use the 2003 manual to guide you?
2 - Did you remove the oil pan, or just the 4 top bolts?
3 - Do you recommend doing both head gaskets even if only one side is bad?
4 - Do you recall how much the machine shop charged you? Any pointers or suggestions about that?
5 - How did you get the crankshaft pulley off?

Thanks! Eurotrash - how did your gasket change go?
 

jbriggsnh

New member
headpitting.jpg

I have a 2004 1gr-fe cylinder #6 HG leak and could not rationalize it from the old gasket. After cleaning the head, I see this pitting between #4 & #6. Is this similar to your observation? Should I have it milled? Head checked perfectly flat (wouldn't pass a .003" feeler on a straight edge). Thanks
 

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java

Expedition Leader
Thanks for the write up, looks like I am going to have to dive in and do this also. I have the exact same symptoms, overheats (gets low on coolant) after long 70+ mph stretches on the highway, fine around town and everywhere else. I do get rough starts after it sits for a couple days though. But exact same symptoms of if I keep it over 2500rpms it will stay cool with a low coolant.....

Did you do the timing chains while you were in there? Seems logical as they are out anyway.... Its another $400 in parts or so. Mine is at 260k now.
 

PrecisionX

Observer
How long did this take you all in? My buddy asked me to help him do his as well as his exhaust manifolds. He thinks he can do it in a Saturday after noon finishing Sunday morning.
 
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