RobzWorkz #7: Improving the 328 Coolant System

Hello again FChat!

If you went through this thread already, you likely noticed that I didn't show any restoration of the pipes on top of the engine. This was in the plan, but I wanted to wait until I had the intake off during my fuel system refurb.

Well, that time is now and welcome to the engine top coolant system refurbishment. This effort shows the refurbishment of the top coolant pipe and the three-sectional manifold pieces.

Since May, I have enjoyed driving the car a bit and waited until now (winter) to do the fuel effort and coolant top. So now I have the car back on jacks and wheel wells out, etc. A simple caveat:

If you are not removing the aluminum pipe from the return riser (on top of the engine just above the blowby oil separator) AND you will not be removing the front lower manifold (just below the intake manifold, held by eight nuts), it is not necessary to place the car on jacks. If you will be removing either of these, you will need access through the rear left wheelwell (you should know what that means). You will have to remove the lower horizontal pipe (even for the forward manifold...it will not come off without removing the return pipe). Removing this pipe turned out to be more involved than expected, but was straight forward.

I will begin with a "before and after" set of pics showing the engine with intake removed before and after engine-top coolant restoration. You can see the NAPA Gold flex lines I installed earlier. Note the "after" pic shows the blow-by system removed, which is being improved as well. BTW, to learn how to remove the intake, please wait until my fuel system thread for this. Recall, I am doing this along with fuel system work and is associated here by convenience.
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To begin here, you will have removed the intake. Also remove the intake air cleaner (filter) housing (it's likely removed already, but can get in the way).

Now, with engine cold, drain coolant from the expansion tank: this is done by removing fasteners holding the tank to the car (two mounts on the side; one on the back), disconnecting the coolant temperature sensor, cracking open the radiator cap and pouring as much coolant into a container located below the radiator cap overflow line. Move/tilt the expansion tank to get as much coolant out as possible.

Then, loosen/remove the lines attached to the expansion tank (at the tank), upper first, then lower, draining coolant into a container each time. I used a large cup to capture coolant from these lines.

After this, I removed the aux air line nuts (you will see a pic below showing full removal of aux air line; if you do this, dont forget the electrical connector as well) and removed the expansion tank altogether (still had some coolant in it--try to keep from spillage). Drain into container. Wash it out

Wipe up coolant not captured.

BTW, do not open the radiator/thermostat bleed screws: this will allow a flow network that will likely entrain coolant via suction and cause much more coolant loss.

Remove as much coolant from the open tank lines by gravity drain into a container. After coolant is removed from the larger (lower) line, enough should be removed to remove the three-piece coolant manifold parts with minimal coolant outflow (next post).

The following pics show my effort at this.
The last pic should be an ample reminder to disconnect any electrical lines (coolant temp sensor).
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Remove the long air injection and blow-by lines on top of the engine if not done already. Clean the engine top to remove trash. I used a shop vac to remove trash throughout all my engine top efforts (use small nozzle; also, I had placed paper towels in the intake openings to prevent any stuff from entering).

Now to remove the upper y-union of the coolant manifold assembly. Begin by removing the small hose that went to the expansion tank. Then loosen the large flex coupling (I removed altogether). Disconnect the electrical connector from the coolant temperature sensor. Then remove the two nut/washer sets attaching the union. I use a magnetic pick up tool to keep track of fasteners.

To remove the union will be easy if not fused to the flanges below (should be gaskets present--mine were fused and needed coaxing); just lift up and pull out from the flex line. If fused, start a defect in the layer at the flange with a razor blade; use a small flatblade screwdriver and a "soft hand" to loosen at one flange (I chose the rear flange) while rocking the union at the flange with the screwdriver, taking care not to gouge the flange. With patience and persistence, you will remove the union and not gouge it. After getting one flange started, the other dislocated on its own. Remove by lifting and pulling out of the flex coupling. Place to the side.

KEEP TRACK OF FASTENERS!!!

Below are pertinent pics.
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Recall, removing the FRONT lower coolant manifold requires removal of the horizontal coolant return pipe beneath it. The manifold will not come off until the pipe is removed.


To remove the lower REAR coolant manifold, first remove the most right and most left edge nut/washer sets so as to be able to remove the clamps holding the electrical lines. Move the lines out of the way.

Place ample paper towels where the flanges are...significant coolant exits when the flanges are loosened. Remove all the remaining nut/washer sets while KEEPING TRACK OF FASTENERS. To remove the manifols, use the same technique described above (razor blade/screwdriver/soft hand method). Remove the lower manifold and set aside.
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Removing this pipe is involved but straight forward:

(Basically, you are opening a way to remove the coolant return pipe out the wheel well)

1. jack (at least) the rear left wheel, remove the wheel and the wheel well liners (DON'T FORGET YOUR SAFETY)

2. loosen/remove the heater hose clamp next to oil cooler; disconnect the two large electrical plugs, and; remove the oil cooler intake tube

3. remove the blow-by system (you can leave bottom hose attached but the other pipes and the separator need to be lowered out of the way (do not remove blow-by coupling on extreme left side of lower rear head that goes to the block)

4. remove the "flex part" of the air injection piping (just the large flex pipe clamps at the check valves)

5. loosen the upper mounts of the oil cooler and push the oil cooler from its mounts

(now, drain some coolant and remove large coolant return pipe)

6. position coolant catch pan below coolant return riser pipe; loosen the flex pipe between the riser pipe on top of the engine and the riser pipe on the left side of the engine; manipulate this flex coupling to drain coolant; the liquid will adhere to the pipe, flow down and drain into catch pan; drain until no more coolant flows (can take awhile); (Note: you will see blow-by separator present in pics of loosening flex coupling---this is because I found out later that I had to remove it---your gain from my pain)

7. remove pipe clamp bolt on top of block just above the flex sleeve loosened; this will allow pipe to move a bit to remove flex couplings

8. remove flex couplings on both ends of the horizontal pipe (I also removed the flex pipe attached to the y-union)

9. remove horizontal pipe through the wheel well; move stuff around to do this (I even had to remove the rear ignition coil wire (at coil; the red wire to distributor).

Below are some pics showing these steps.

(The good thing for me that warranted these steps was that I was reconditioning much of this stuff for my fuel system effort)

Now you can remove the FRONT lower coolant manifold with the same method as with the rear one.
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Now's the time to clean the engine top surface and prepare the flanges for receiving the lower manifolds. I disconnected all the electronics and moved the wiring out of the way. Then I used an XACTO knife and a razor blade to remove the old gasket material from the flanges, during which I used a shop vac to suck out all the debris. For the rear manifold, I used a mirror to view my effort.

When cleaning, I used lacquer thinner and final prep was with acetone.

I also did some cleaning of the wiring harnesses as well as cleaned connectors while there.

nice and shiny!!!

Pics below:

Note: last pic shows that I attached a small hose to my shop vac so I could clean out the orifices a little (sucking out a very small bit of coolant is fine).
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To restore the lower manifolds, I first remove old gasket material with an XACTO knife and razor blade. Then clean and dry with lacquer thinner. Then used a DREMEL with a wire wheel to shine it up. The pics show a before and after comparison.

Prep the manifolds with acetone and use RTV (I used Ultra Black) on the flange/gasket surfaces. Install the manifolds not too tight...just enough wrist to know the flanges are seated...wait a hour for RTV to cure, then tighten wrist tight plus some (no torque specs available).

Note that I used ample RTV here, unlike for other systems: since coolant passages are large (the smallest being in the radiator and at the thermostat start-to-open; this isn't like oil, where the smallest passages are in between bearings, etc...much well under 10 mils), I felt it worthwhile to use more RTV to prevent corrosion, especially outside the internals of the system (like around the water pump o-ring and bolts). However, after applying ample RTV, I did use Q-Tips and rubbing alcohol to remove the bit of RTV just inside the flange/gasket openings (no more than 1/16" removed from the lip), prior to installation, to account for pressure expansion there and minimize later flake-offs.

After installing, clean off the area with acetonr to remove RTV and shine it up again.
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I found it necessary to remove the pipe so I could check its integrity and clean/reinforce it for long-term use.

I cleaned it up with acetone. Also notice that the tube going to the expansion tank was bent. So I reshaped it to round by using a long socket as a backing and a plastic hammer to reshape...use soft hammer blows for this..clean again with acetone. I then reinforced the joint with QuickSteel epoxy putty after roughing up the joint with a file. Notice also that I had a few through-pits in the pipe; the QuickSteel filled these; after curing, remove any epoxy that entered the inside via the through-pits. After this, I shaped up the reinforced area with a small file and sandpaper.

Now reinstall the pipe (be sure the FRONT lower manifold is reinstalled). This is done with significant work while trying to minimize coolant spillage from the riser pipe. Tighten all the flex sleeves into place first (I also place some old hose around the pipe to protect from metal-to-metal chafing). Then install/tighten the pipe clamp wrist tight plus some (estimated about 10-14 ft lbs). You can reinstall the other services if you like (I didn't since I was refurbing these systems as well...I certainly did do a lot of cleanup). You can see that the rubber protector on my pipe clamp deteriorated and was removed. Instead of buying new, I used some bike tire inner-tube as the protection.
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This particular pipe presented some restoring questions.

First, the small tube for the line to the expansion tank was heavily corroded and quite permanently fixed to the y-union: I felt that trying to remove it would cause damage to the y-union, so I decided not to remove but reinforce with QuickSteel. To do this, I felt it necessary to remove as much of the corrosion as possible to expose the metal for QuickSteel adherence; this I did with a small file and an XACTO knife (be sure to use the sharp point to dig out stubborn corrosion in pits). Also, there were two through-pits in this line (larger than the ones in the return pipe above...clean these out to metal as well).

Second is the presence of the coolant temperature sensor: since it worked before I did this effort, I felt that, like with the small tube, I could damage the y-union if I tried to remove, I chose to leave it alone, and just polish it up with the DREMEL and wire wheel.

As with the other manifold pieces, I used an XACTO knife and razor blade to remove all gasket material, cleaned with lacquer thinner and dried; then polished with the DREMEL.

Clean the entire piece with acetone very well. Then apply the quickSteel to the small tube.

After the QuickSteel cured, I shaped the tube, first with a small file, then with progressive sanding (up to 1500 grit...make it fairly smooth).

Now install the union with gaskets and RTV as with the lower manifolds. Install new hoses and the expansion tank, etc.

Fill coolant system and check for leaks. Mitigate as necessary.

Remount/connect electronics.

After reinstalling the intake and the rest of the engine, before running, make up coolant. Run to hot and thermostat open...cool down and make up coolant again. Use bleed screws to release any air in the system (you can do cold or with a little manageable heat).

Note: since I used significant QuickSteel on the y-union small tube, and it is mildly pourous, I applied a tiny bit of RTV all over the small tube before installing the small (red) hose onto it; you will need to tighten with a clamp on it to hold into place and let cure, then ensure tight (hose should not slip at all).

All done! Now to the fuel system.
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Thanks for the heads-up on the oil separator, Iain.

All the studs throughout my effort were in good shape; they just needed a good cleaning. I am well-blessed with an engine that seemed cared for by PO (I think it was used for track and was maintained well...don't have a history, though).

Also, I did replace both crank sensors (I got from Superformance and had to reshape the mounting holes...BAD SUPERFORMANCE!!! They looked identical and had the same internal resistance as the ones removed, so I used them. BTW, Superformance is a great group, so only one issue with them thus far!). Pics attached below.

I totally missed the o-rings (didn't see any upon removal, but just now did check on TRutlands diagrams, and they are there; I also noticed in my pics that there are bevels in the stud holes which would indicate place for the o-rings). Since I actually inserted RTV into the stud holes, and gooped them up well, I feel that I will have minimal corrosion. However, I will keep this in mind: I will be doing engine-out rebuild in several years or so. Thanks for that catch.
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Nice work Constance!

Your tube had more disintegration than mine (mine had plenty of integrity left to hold itself and coolant pressure). Like yourself, I would have cut it off, re-drilled/tapped the hole and installed helicoil and new tube. Excellent machine work as well.

 

He did mention that Hill engineering had the fittings. You will still need to remove the original and tap new threads.

 

Menno, when I did mine, I didn't see sealing rings nor spacers (thus I don't know if part 34 is metal, plastic or rubber). I used ample RTV to seal. No problems yet since the work was completed.

Also, check for any cracks (in the union or in the block).

FYI for all, I use "ample" RTV for cooling system seals, which is not always supported by the forum. However, since cooling passages are large (smallest passages I know are in the radiator, between the fins), and I didn't want to machine surfaces for dry flatness, I chose the RTV; thus if any slag RTV comes off, cooling should not be affected.

This is very different for engine oil passages...don't want anything in there if possible; the only RTV I know for that system is the touch areas beneath the valve covers where the gaskets are partitioned.


BTW, how did you remove the hose fitting without deforming it?