logsurfer

I'm sorry to hear about the fate of your HG. I hope the rebuild all goes well.. Please take pictures while working on it, I know the Yotatech community will appreciate it.


Happy Thanksgiving!

rustyshakelford

mine does the same thing when its cold. its also leaking coolant out what appears to be the water pump. i bought the tacoma used with 209000 miles, but the previous owner told me the timing belt, water pump and HG was recently replaced. I flushed the coolant system but it seems to be leaking out a little bit everyday! the exhaust doesnt smell sweet but i do smell the coolant right at the motor

brett

xcmountain80

This is a term and or process which I am unfamiliar. But no I planned on replacing the gasket.

Thanks for the input.

A

xcmountain80

Likely a faulty water pump gasket.


A

mastacox

As a general rule, aluminum heads should be "decked" (sealing surface machined flat) every time they are removed to help ensure a good seal. It's possible your heads will seal OK without getting a machining operation to flatten out their sealing surface, but there is a risk there.

You will probably have the replace the gaskets between the heads and the lower intake as well, they are a single use gasket since they have an o-ring that seals a coolant passage that tends to rip apart when you take the lower intake off.

xcmountain80

I just replaced the intake gaskets a week ago so they will be fine, and I will likely have to do it again when the SC goes on. As far as decking the heads I'm having trouble envisioning this. Are we talking about the lower portion of whatever the valve covers attach to? If not then pulling motor to machine the top portion of the actual block wouldbe necessary (and I was going that far I'd have the motor rebuilt while it was out.)

Aaron

mastacox

Not the block, the heads. The block's sealing surface is usually fine, but the heads' will tend to warp over time with all of the thermal cycling. The kind of head gasket used on our engines requires a very smooth sealing surface.

This is the surface I'm talking about- the bottom of the heads:


The problem is, to get the heads decked you have to have them disassembled valves and all, which usually means you get the heads rebuilt while they're all apart. Also keep in mind, according to the factory service manual you can only take off .007" to get them flat. If you have to take more off, you need to shim the heads... Again this is according to the FSM, and some head rebuild shops have differing opinions on the subject, because the valves never actually come within .007 of the piston; but there's probably a reason Toyota put such a tight tolerance on it.

xcmountain80

Hmmm well I'm just not sure, if I'm going through all that I would look through the LC Engineering catalog and pick out some nice bits and pieces for a total rebuild. I have a LCE dealer local so that wouldn't be a problem, but again if I Have to take them down I will be steering toward an entire rebuild as that would be 1/2 ass (just rebuild the upper and not the lower). Though thinking about it I can hit it with a light 1500 sanding block and add some RTV and tada .... might not work as its a high pressure application but sheesh .007 is almost like not doing anything. Though there are always these....
http://www.toyotacatalog.net/M1WebGe...A-CBC6FC983502


Aaron

mastacox

Well what can I say, I just rebuilt my top end because I didn't have time to pull the whole engine. When I pulled it apart, you could see the factory hone cross-hatching on the cylinder sleeves, so I doubt a bottom rebuild was really absolutely needed.

$3000 is a lot for a pair of performance cylinder heads. I got my rebuilt set from a shop in Florida for $650 shipped, and that included return shipping labels for the old heads. If you're not going to get the heads decked, just scrape the old gasket material off with a plastic gasket scraper so they're nice and shiny, and bolt them back on. Don't use sandpaper by hand- you could do more harm than good in terms of overall flatness.

xcmountain80

I'd be interested in knowing who and where in FL as I live here and would like to discuss some things if they are that type of business. Did someone say port and polish? Jk but if you have the info it would be appreciated.


A

mastacox

These are the guys I used: Clearwater Cylinder Head Inc.

They were knowledgeable, and have good customer service. Highly recommended!

xcmountain80

Funny thing, the truck hasn't missed a beat on startup and didn't throw the p300 code again though it did throw a p1135 code which has me stumped.

A

pruney81

Your thread is 7 months old, from my experience a head gasket failure is pretty obvious with symptoms and performance. Is it blown or not? I think if it was blown by now the truck would be running pretty crappy. I find it hard to believe that it has a blown head gasket and you've been driving it like that for 7 months and you haven't had to add any coolant and it runs good. Wouldn't the head gasket leak get worse over time? Just throwing out some ideas.

mastacox

Mine took about 6 months from the time I first started noticing symptoms, to when it had gotten so bad the engine would barely start. I don't think it's unusual; it all depends on the number of heat/cool cycles you have gone through in that timeframe, and how much you drive it.

Sweet smelling exhaust and a lot of extra precipitation in the exhaust on start up are definite telltale symptoms of teh HG going out, probably in the same spot mine did: