4.6 v-8 help needed

[bens97tbird]

My '97 t-bird is puking coolant out of the reservoir tank when it's under load (whenever you stomp on it).... it won't do it when it's sitting in park and you rev the engine. I've replaced the thermostat, reservoir tank, and the cap. I'm beginning to think the head gasket may be bad??? no normal head gasket symptoms though, except I think I smelled combustion gasses out of the coolant reservoir when I put the parking brake on and gunned the engine while in gear to make it spit up... it runs good with plenty of power, just pukes coolant. Any ideas?

 

[007_SuperCoupe]

bens97tbird,

It sounds a lot like head gaskets. It's hard to diagnos from a keyboard though. If you dare driving it, get it to a good mechanic's shop. They can perform a chemical test on the coolant that checks for oil. If you're getting exhaust in your coolant (sounds like you are) then chances are very great that you're getting some oil in there too. If driving is not really an option (and I don't really recommend it) then call the shop and find out how much coolant they need to do a chem test on it. Then you can just take a sample in to them.

At this point, I'm guessing that it is a small leak in the headgasket. This "hole" opens up significantly on the burning of the air/fuel in the combustion chamber. Under load, the car puts more air and more fuel intot he combustion chamber creating a larger explosion. This is why you only see it under load at this point. It will get worse and it probably won't take long. One thing also to consider if it is the head gaskets is your O2 sensors and catalytic converters. Neither of those like coolant and if you get enough dumping into the exhaust, chances are that you'll need to replace them. I say, fix the problem now, then if you have CE light and/or the car is running warmer than usual, you should go ahead and replace the O2s and the cats (with high flow replacements). Just want to let you know to expect something, although if you have caught the head gaskets soon enough, those things will be fine. Just don't be surprised if within 1k miles, those too need to be replaced.

 

[bens97tbird]

thanks for the informative reply, I pretty much figured the head gasket was done, but was hoping against hope??? lol. Anyway, now that I'm committed to fixing it.... it's got close to 160,000 miles, so I'm concerned about what I may find when I tear into it and how long it would last afterwards so I'm probably going to get a long block and just change out the engine. My question now is: will the computer operate a 32 valve version? The difference in cost is only around $300.00 for the purchase, so I want to see what else I may have to do to it.

Thanks

 

[007_SuperCoupe]

Going to a DOHC setup is much more than just a computer swap. I'm not real familiar with the 4.6, but I know that the swap involves just about everything from accessory brackets to wiring, etc. A 2-valve can be made for decent power though and not too hard. First thing that you'd want to start with is upgrading to the PI heads and intake as a base and go up from there. The short block may not need to be replaced due to damage from a blown HG, but if you're looking to make more power, then it wouldn't be a bad idea at 160k. I'd suggest getting a set of PI heads ported by a reputable head porter, then get some custom cams to match. Decide now if you want to go forced induction (centrifigal supercharger is easiest on the T'Bird 4.6, but positive displacement is available) or not or even N2O. The cams you get ground should take this into account. With bolt on parts, including the PI upgrades, you should be able to make near 300 rwhp n/a. Then you can add a supercharger and bump that up significantly.

My suggestion is to stay with the 2-valve platform, but upgrade to the PI stuff and maybe think aboug forced induction. There's a lot of hidden costs though either way you go. The most cost effective way is definitely staying 2-valve and upgrading that as much as you can. There's a ton of information out there on that. Have you looked at www.********* yet? That would be the place that you'd get all the answers on the V8 that you could ask. Many guys over there have done this upgrade (PI) as well as superchargers, nitrous, and there's even a few DOHC guys over there. They know a lot more about that than I do...I'm a SC guy, that's what I know about! The rest of the stuff, I have a working knowledge of but not detailed knowledge. Hope this stuff helps you out.

 

[bens97tbird]

hey thanks again, yes I just visited the tcoa site and I think I'll stick to the easier route with the PI heads and intake option.

Have a great evening!