El Camino Central Forum banner

1 - 20 of 42 Posts

·
Registered
Joined
·
61 Posts
Discussion Starter #1
Yesterday I took my car out for a short drive and when I came home I noticed it was idleing a little high. Around 1000 rpm in park. Anyways today I drove a bit more and I noticed that now it is idleing rough in park going up and down from 400 to 800 rpm. I checcked the oil dipstick and it was wayy past the full mark. And when I checked the trans fluid it was almost completely empty. Is it even possible for the trans fluid to do this? The oil itself wasn't murky just dark which I thought was odd since I changed the oil myself 400 miles ago. What could cause this?
 

·
Premium Member
Joined
·
2,458 Posts
The trans modulator valve is bad..diaphram blown ! will suck trans fluid ito engine easy fix . you will need to do a oil change,and you will need to just bring trans up to level !! There you go ...

get the one with red line around it . any parts house !!!
 

·
Registered
Joined
·
61 Posts
Discussion Starter #4
Great! Thanks for the info. Looks like I'll have to pick that up today. Unfortunately I'm not much of a mechanic. Im guessing this isnt something I should try and go alone. Unless there's a writeup to do this sort of thing.
 

·
Registered
Joined
·
1,348 Posts
Well, it's pretty darn easy. You have a TH350, right?

On the right side of the transmission, not far behind the bell housing, you'll find a vacuum hose connected that runs up to your manifold. Pull it off the little modulator (it looks a little like a fuel filter).

Loosen the hold-down clamp's bolt and pull the modulator out. Put the new one in. Install the clamp and bolt. Install the vacuum hose.

What gets tricky is adjusting the modulator, if it's an adjustable one, to the kind of shifts you want. The transmission experts here can tell you how.

Or, you can go to a transmission shop and they can do the whole job for you for probably less than $100, maybe a lot less.
 

·
Registered
Joined
·
61 Posts
Discussion Starter #6
Seems simple enough. I can definitely do that. How can I figure out if the modulator is adjustable or not? And what kind of differenece would the adjustment make?
 

·
Registered
Joined
·
1,348 Posts
Someone up above said to get a certain modulator. One with a red line around it? There should be instructions with it. You adjust it by inserting the proper-sized allen wrench in the connection for the vacuum house, and turning it. Don't ask me which way; it's been 10 years since I messed with mine on my T.

I'm not sure I made it clear that the modulator is on the transmission. It looks a little like the vacuum advance for a non-computerized distributor.

At the parts store, ask for a modulator for a 3-speed automatic of your chosen year.
 

·
Registered
Joined
·
61 Posts
Discussion Starter #8
Okay! Today I decided to try my hand at replacing the transmission modulator. I got under the car and I've decided that there simply isn't a modulator on my transmission because I looked everywhere. I checked Google for images of where the modulator is on a TH350 and TH400 and it wasn't in either place. I guess this means I don't have these transmissions which is odd because I have a 305 and I guess these are the most common for my engine. I guess the first step from here is figuring out what transmission I do have. Anyone know how to go about doing that?
 

·
Premium Member
Joined
·
5,787 Posts
A modulator equipped tranny is the only way I can think of to get trasnmission fluid into the engine. there is no other fluid or vacuum connection between the two.
 

·
Registered
Joined
·
929 Posts
Hey Jay, on your shift indicator does it go (D) D 2 1? Is it an overdrive transmission? You probably know this, but none of the transmissions you mentioned came stock in our caminos. Needless to say 700r4s have been swapped in countless times, it just doesn't justify the fact there is ATF fluid in your oil.
 

·
Registered
Joined
·
61 Posts
Discussion Starter #15
It does but the indicator isn't functional anymore. The Previous owner installed one of those B&M shifters presumably when he changed the transmission. The previous owner did alllot of work on the car that I wasn't aware of. On another note I'm almost positive that it's a 700r4. Just remembered it's got that trans cooler up front. This ones really got me stumped. There doesn't seem to be anyway the fluid could be getting into my oil. Also I know I didn't mention this earlier but there are no leaks under the car when I park it and the transmission is definitely still loosing fluid. It started to whine slightly today.
 

·
Super Moderator
Joined
·
4,363 Posts
Is it possible the PO installed a drain plug on the trans and you drained it and added oil to the crankcase? Seen it before, you would not be the first!
 

·
Registered
Joined
·
2,168 Posts
I would also worry that the diaphram in the fuel pump has ruptured and filled the crankcase with gasoline....much more likely than getting transmission fluid in the oil. Even if the modulator valve is bad that would only get the transmission fluid into the intake then the combustion chamber and out the tailpipes putting up quite a smokescreen....it would not go unnoticed. The rings in the engine would have to be horrible for the transmission fluid to make it to the crankcase. If the transmission is indeed low, I'm betting it is coincidental...check that oil for fuel contamination and get it and the fuel pump changed immediately......Dan
 

·
Registered
Joined
·
61 Posts
Discussion Starter #19
Alright I guess that's my next step. What should I look for in the oil? It actually crossed my mind that the crankcase might be getting filled with fuel. I smelled the oil and it didn't have a distinct gasoline smell. Also would gasoline in the oil cause it to go brown. Thats what I was getting.
 

·
Premium Member
Joined
·
2,458 Posts
Yes it can,and gas in the oil is very corrosive to the engine parts,go ahead and drain it out and see how it separates ??:beer:
 
1 - 20 of 42 Posts
Top