Transmission and Gasket questions.

Hello I am a first year college student and I bought a 2005 Tacoma Prerunner 4.0 In February 2022. When I got it home I saw that there was oil in the coolant so I flushed the coolant system and I never got any gasket symptoms. It had 106,000 miles apparently and I've put on 8,000 since with no major problems. It had this problem that when I'd accelerate and around 30mph it would Start vibrating like if you were driving on the side of the freeway with those loud bumps. It would go away if I stepped on the gas more. I fixed it by flushing out the transmission fluid and changing all of the sparkplugs. I finally tried to do a gasket test with that blue liquid but when I do it on the radiator, it sucks fluid. Is there a better way to test a gasket or a better way to confirm the state of your engine ? I also wanted to ask some stuff to see if any of you guys have this in your trucks. When its in park and I shift it into drive or reverse, it jerks forward or backwards depending if its on drive or reverse. Also when Im at a stop and start driving down hill it only makes it to 4th gear and doesn't shift to 5th so the RPMs go up. It won't shift until the ground is flat. Last the whole bottom of my truck is covered in oil. Like the transmission pan and the frame. How should I go around diagnosing the oil leak. I'm not too car savvy and I was hoping you guys can help. Thank you happy holidays

 

Well, oil in the coolant is weird but better than coolant in the oil. Was it engine oil or transmission fluid? The latter would indicate a broken radiator because trans fluid gets circulated thru the bottom of it. Stop using those stupid leak test or stop leak bottles from vatozone. They never made a mechanic in a can, and they never will.

If you’re worried about your head gasket (which, honestly, on an ‘05 you should) you can do a compression test. If you can do spark plugs, you can do that, too.

for the shifting issue, could be lots of things. Did that start after you flushed the trans? Maybe you got the fluid level wrong. How did you flush it?

for the oil mess, clean it up first and then keep an eye on it to see where it returns from.

 

Hello Hx989 thank you for replying. I will do a compression test as soon as possible. About the flush, I took it to the dealer to get it flushed. I was doing some research about the downhill driving and I think it might have something to do with engine breaking. Can you explain a little bit more about the trans fluid circulating through the radiator? I've never heard of that. Thank you again.

 

Stop leak is generally bad, yes. A combustion gas tester is in no way in the same league, in ability to cause other problems, or in hackyness. Having combustion byproducts in your coolant is generally a pretty solid sign that you have a blown head gasket.

A compression test is a terrible way to find a blown head gasket. You can have crap compression & head gaskets that are sealed just fine, or you can have a pretty screwed head gasket & still get good-looking compression numbers. Good compression means you have good compression (granted, a totally pooched HG will give low/0 compression, but I've personally only seen that with old composite HGs) and low compression just means something isn't sealing well. A leakdown test gives a more meaningful, less instantaneous result, although you still need to figure out the where (but it makes that easier, too)

 

Do you have a check engine light on? If not, and if you don’t have drivability issues, misfires, or coolant in the engine oil, then i probably would not worry about a compression or leak down test.

Yes, the trans fluid goes through the bottom of the radiator so that it reaches operating temperature faster; also helps to cool it some (if you have the tow package, there will be an additional cooler in front of the radiator). So if the radiator is broken the coolant and ATF can mix but it’s honestly more likely that coolant goes in the ATF than vice versa due to gravity and pressure.

Can you try to better explain what exactly is wrong with your truck NOW?