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Fuel pump and oil pressure problems
Driving to the club meeting at the end of April, my TR4 broke down. The spindle holding the lever arm on the fuel pump had come loose and the lever had fallen into the sump. So the poor car suffered the ignomony of being brought home on the back of a low loader!
Obivously the car would need a new pump and the sump would have to come off to retrieve the lever, but on the bright side it gave an opportunity to investigate some erratic oil pressure readings.
My thanks to Mike and Terry for coming over and helping me sort out the problems. Well lets be honest they sorted out the problems while I looked on!
First lets look at the fuel pump......
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In this first picture you can see the spindle (arrowed 1) that worked loose. You can also see the spring for the lever arm (arrowed 2) that had jammed in the pump housing. At least we new where it was!
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In this next picture you can see the lever arm sitting on the sump baffle once we had removed the sump. We could reassemble the old pump by simply reattaching the spring and lever arm, but we didn't want to risk it all coming apart in the future. So a new pump was fitted.
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Road testing the car and we ended up with petrol flooding from the vent hole on one of the carbs. The consensus was that we had exposed problems with the floats or jets. So over to Mike's to strip the carbs down.
The first thing we found was a bit a rubber in the jet. We managed to get it out and the jet appeared to be OK. The float also appeared OK so we reassembled everything fitting new O rings and gaskets.
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The float in the other carb looked as though it was beginning to disintegrate, but the jet appeared OK. So we ordered a new float and at the same time got a couple of spare diaphrams as one was begining to show signs of age.
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With the new bits fitted we managed to get the car started but it was not running well and petrol still came out of the carb vent hole. Paradoxically when we took the other carb apart there was no petrol getting into the float chamber - that would account for why it wasn't running well!
Looking at the new float it sits very tight against the central pilar and we thought it might move sideways during operation and be sticking against the central pillar.
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You can see in this picture how the old float fits with no opportunity to move. To test our theory we put the old floats back, reset the float height and reassembled everything. There was still a bit of flooding from one carb, but this was solved by setting the float height slightly higher, thereby exerting more pressure on the float jet.
A road test confirmed that we were getting no more leaks, so the car is usable again. However, after making enquiries from various suppliers it appears that the proper floats for the carbs are no longer available, so I will need to keep my eyes and ears open and hope to find some somewhere.
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....and now a look at the oil pressure problems
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Whilst we had the sump off it gave an oppotunity to investigate some erratic readings on oil pressure. The pressure by-pass valave didn't seem to work when the engine was cold giving readings in excess of 70 psi, and once warmed up the oil pressure on tick over was sometimes as low as 25psi. More worryingly whilst running the pressure would sometimes flcutuate between 50 and 60 psi for no obvious reason. With the sump off we could check the oil pump, but this appeared to be fine. The next areas to check were the 2 valves in the filter housing.
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We removed the pressure bypass adjuster mechanism and removed the spring and ball bearing. On inspection the seating looked damaged and the ball wasn't sealing correctly. You can't replace the seating, but using the old ball, a suitable piece of metal and a 4lb club hammer we were able to repair the seating. Fortunately we also had a new ball and spring to put in as we reassembled the whole lot. The picture shows the new ball (arrowed) in its seating. There were similar problems with the other bypass valve and again applying a hammer (lighter this time as the seating is aluminium!) we managed to get a good seal. We had released the adjustment on the pressure bypass valave before reasssembly with the intention to adjust it as necessary once the car was running.
The car started and oil pressure got up to around 50 psi initially. Small adjustements brought the pressure to 70 psi at 200 rpm , but revving the engine didn't cause the pressure to rise any higher, so that problem seems to have been solved. Once the engine is hot the tickover pressure is about 40psi which is better than before, but we will need to keep an eye on it over the coming months to see what it is like in normal use.
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