HT4100 4.1, 4.5, 4.9 Discussion, 4.5 intake manifold gasket progress in Cadillac Engine Technical Discussion; Some of you might remember last fall I started replacing the intake manifold gaskets on my '90 Eldo. I got ...
Some of you might remember last fall I started replacing the intake manifold gaskets on my '90 Eldo. I got it tore down, then got sick with pneumonia. with an additional school load from getting sick, then just plain getting lazy, I left it sit all winter. Today I took advantage of the weather and got back on it.
I'm done for today to celebrate St Patty's with my girlfriend. Slow process as everything needed to be re-cleaned from sitting all winter and also I'm slowly remembering how everything goes back together...
Wow.. so the rods go through the manifold? What a strange design. I took apart a ford 5.0L once and the lifter valley was covered in wax and sludge. Turned out the previous owner use nothing but quaker state oil. Yours looks nice and clean. Its a shame you have to remove the rockers and stud girdle just to change the intake gaskets. Ive read alot of threads about the girdle cracking after re-installation. Apparently its very sensitive to its torque specs. If you need any info from the FSM let me know as I have have the same engine. Same body color too it appears.
Yeah, it's not that bad though. In fact, the thing that makes it the easiest is the rocker support. Just have to remove the support bar rather than removing each individual rocker.
The design is similar to the GM 2.8, 3.1 and 3.4 engines. The design allows for better packaging since the engine doesn't have to be as wide, externally. However, it doesn't allow for very good breathing heads, which is the 4.X's downfall when it comes to performance, especially high RPM.
The rocker supports usually crack from incorrect install and removal. You can't just remove each nut one buy one. You have to cycle through them all, tightening/loosening little by little as the valvetrain is compressed. If you remove one nut completely without the others, the force of the corresponding valve spring will crack the support in that spot.
I torqued the main rocker support nuts to 37ft/lbs. What does the FSM say? Hopefully nothing wildly different as I already put the rear valve cover on, as you can see from the pictures.
Don't know about the 4.5, but the 4.1 oil drain-back from the top of the heads is a bad design. It drains alongside the head bolts into the lifter valley. Had to fool with mine, blow them out etc. Sludge seems to collect there, and bakes in there.
I was afraid to remove any head bolts to clean it better. I visualized a heli-coils nightmare