VX Sump Foam
Ever since I bought my 1600 VX Classic the question over the condition of the sump foam had been nagging away at the back of my mind. The car is 20 years old and came with no service history - how often had it been changed ? Maybe never ?
An oil change was now due and it was time to bite the bullet. I've dropped a few sumps - how hard could it be to take a look? The only slightly unusual aspect of this one was the double gasket and baffle plate arrangement. (Sump-gasket-baffle-gasket-block.)
So, drain the oil and take out all the sump fixings - easy*. Tug at the sump to separate it - no go, no surprise. Try to find somewhere to lever it off - hmm, nowhere very suitable. Tap it a few times with a rubber mallet - nothing. Hit it harder - oh-oh, still nothing. Hit hit as hard as I dare with a 2lb club hammer via a wooden block - it laughed in my face. Time to stand back and re-group.
It was clearly going to need a considerable amount of force to break to seal, and the obvious place to apply it was against the triangular extended sump flanges next to the bell housing. There's enough space to get a G-clamp in there, but then there's the problem of what to pull against. A wooden beam across the car spaced down with blocks from the side chassis rails would do the job, but luckily I had the car up on my home-made four poster so could clamp some steel angle between the ramps and use that together with some 8" clamps.
*( 2 x M10 through the bellhousing. 14 x M6 into the block - 2 long at the rear, 2 medium at the front, 5 short ones each side. )
This eventually did the trick, and the gaskets started to separate at last with that satisfying crackling sound.
... But... each gasket had only partially separated in various places above and below, and as with considerable difficulty I struggled to free them further the baffle plate was getting bent. The lower gasket was still solidly holding the plate to the sump, meaning the sump was still not free to drop, with the oil pickup pipe being jammed between the two. At some point it became clear the pickup pipe had come out of its support clip - things weren't going well.
Two hours into what should have been a simple job, after a long slow process of hammering a dull knife blade round between the baffle plate and sump gasket, it came free, the pick up pipe could be unbolted and the baffle removed. Then followed another hour cleaning off the remains of the gaskets, and straightening the plate.
I'm guessing the sump might never have been off before, but the foam was completely intact with no sign of degradation whatsoever, just compressed... A little annoying perhaps after all that effort but also something of a relief.
After test fitting the pickup pipe and bending it back to fit into the clip, I thought it wise to check the clearance to the bottom of the sump. But what should I aim for? A search threw up this slightly oddly worded document from Caterham, which although not directly relevant gives what seems a reasonable figure to aim for:-
Although this mentions using plasticine to test the gap I didn't relish the prospect of repeatedly fitting the all the parts each time an adjustment was made. A cobbled together gauge that indicates the height of the sump floor seemed an easier solution:-
The height of the gauge was the sum of:-
Depth of sump at pick up position (n.b. others castings may vary) = 60.7mm
+ lower gasket 2.4mm (metal inserts)
+ baffle plate 1.5mm
+ upper gasket 2.4mm (metal inserts)
for a total of 67.0 mm
Holding this against the bottom of the block showed there would be no gap under the pipe. This however didn't appear to be the result of it having been distorted - the opening of the pipe was already at an angle which would only increase if the pipe were to be bent further upwards. Marks on the sump suggested that the pipe may have indeed been touching and perhaps only the fact that the end was cut at an angle had allowed oil through...
The pipe was repeatedly cut, filed and test fitted until a 3mm drill would pass between the pipe and the gauge.
The cut edge was rounded smooth (for possibly superstitious reasons).
The pick up flange o-ring was replaced with a BS114 which was to hand and was a perfect fit.
The (£50+!) foam was supplied by Caterham, but the two gaskets are cheap standard Vauxhall parts:-
# 90411386 (Elring 763.934)
The dipstick had rubbed a notch into the old foam, so it seemed sensible to create clearance in the new foam:-
Foam dimensions, showing position of cutout to clear the dipstick.
Baffle straightened and cleaned up.
The thickness of the foam means it has to be be compressed significantly as the sump is lifted into place.
To make assembly rather easier, M6 x 100mm long studs were fitted into four 'corners' of the block. Now the use of studs is an old trick, but on their own don't solve the problem of holding two floppy gaskets and the baffle in place with one hand while reaching for the sump with the other. The solution lies with the humble wooden clothes peg...
First, dabs of silicone sealant were applied at the four joints where the oil pump and rear main bearing cap meet the block.
The upper gasket was then raised into position and held with the clothes pegs. (Squeezing the jaws onto the thread creates grooves which improves the grip noticeably.)
The baffle plate was raised into place and the pegs moved under to support it while the pickup pipe was fitted. (The two bolts at the flange torqued to 8 Nm and the one securing the bracket to 6 Nm .)
Similarly the lower gasket could be supported while the sump was lifted into place onto the studs, pushed up to compress the foam, and one of the front medium length sump screws fitted each side. (These are long enough to support the sump with the pegs in place.)
(N.B. From this point on thread locker is applied to all screws .)
The pegs could then be removed, the sump pushed all the way up and three short screws loosely fitted on each side and the two long ones at the rear. The two medium length screws were then moved to the front, replaced by two short ones, the studs removed and replaced by four short screws, and the M10 screws fitted through the bellhousing.
The screws in the block were tightened gradually alternating with the bellhousing screws so as to make sure the sump was pulled in fully against both surfaces. The M6 screws were the torqued to 15 Nm . I didn't have a torque figure for the M10s so just tightened to what felt about right. (Edit - assembly guide states 34Nm.)
Onto the home straight:
The refill took more than 4 litres. Rather more than I had read, but I think a combination of changing the foam and having the sump off over a couple of warm days had drained every last drop. The pump was so dry it couldn't bring up any pressure cranking with the plugs out and ECU disconnected (which was a little worrying...), but with fingers crossed it came up to pressure immediately I ran the engine.
In the end little has been achieved for all that effort, but peace of mind is priceless, and hopefully it'll be easier next time around...