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Admin · Posted: Sun Sep 07, 2003 3:48 pm Post subject: Big End Bearing Shells

Hi

A while back I mentioned my P4 had developed a minor knock at certain revs once warm. I decided to replace the big end shells, on the basis this could be done with the engine in the car and they are cheap. Any major investigation would require dropping the engine and I would rather risk wasting the cost of a set of big end shells (around £30).

Anyway finally did the job today (not having used the car for about a month). These are the old shells. Anyone with more experience of rebuilding 4 stroke engines care to make any comments?

All the shells together

The shells for no 1 cylinder. Furthest form the oil pump and the most worn.

The shells for number 3 cylinder. Noticeably deep score in the middle

All the best

Keith

Gary UK · Posted: Sun Sep 07, 2003 8:32 pm Post subject:

They seem very scored (all of them).

Admin · Posted: Sun Sep 07, 2003 9:41 pm Post subject:

Hi

Talking to a few people the best suggestion so far is that the oil pump is fubar. Is there a decent take off point to check the oil preasure on a 16V 33?

All the best

Keith

Matt Stolton · Posted: Sun Sep 07, 2003 11:31 pm Post subject: Ouch

Nasty looking set of shells. I've only seen worse ones in 2.0TS engines that run out of oil....

A good spot for oil pressure, is the bolt which is to the front of the inspection hole of the flywheel. From memory (and don't quote me on this, I did my sensor about 14 months ago) you need a M14x1.5 threaded adaptor to your oil pressure sensor. For oil temp, I used a T adaptor peice from where the low oil light sensor is.

Given that you know a thing or two about maintaining your car, I won't insult you by asking you whether you checked the oil level Wink

Is this the engine that got wet and blew the head gasket? I wonder if the oil/engine has become contaminated with water (either from the inducted water, or head gasket) leading to an oil with reduced lubeing abilities. Another daft idea is that you may have cracked a bore as a result of the water incident, which is now letting water into the oil.

One daft idea is whether you have any excessive end float on the crank, leading to out of square travel of the bottom ends relative to the crank. This is what happens on the 2.0TS engines, only the crank is located properly, it is the big ends that wander out of square, especially if they are underlubed.

To score all those shells so badly, you must have had an event that was common to all pistons. The low pressure or contaminated oil idea is good and would be global to all shells, but it must be worth checking that the crank isn't loose, as excessive movement of that would lead to all shells becoming scored.

Best of luck.
_________________
Regards

Matt

Ex Alfa 33 'GTA' (P4 with Knobs On)
Now cruising in a 166 3.2 Ti!!

Admin · Posted: Mon Sep 08, 2003 10:53 am Post subject:

Hi

The engine does seem to have developed an appetite for oil. I don't think it has ever been that low though.

Oil pump is the first thing I want to check. Also it seemed to take longer than I expected for the preasure warning light to go out when I started the engine again after changing the shells.

Thanks for the comment on where to plug in a preasure tester. Just have to buy one now Confused

.

The was no "vertical" play in the big ends that I could feel even with these shells. There is a tiny amount of horizontal play, but without stripping the engine I dont think I could do anything about this anyway. From what I could see of the bores they still looked good with the cross hatching still clearly visable.

It does seem that number 1 big end bearing is the worst, and that is the one furthest from the pump. There were no marks on the crank. This is not the engine that got driven through a puddle, it is the 2nd hand engine that I got to replace it so I do not really know its history (or why there was a 5mm x 3mm x 12mm piece of plastic floating round in the sump Shocked

). I have dropped Paul Lewis a PM as I think I might well be best off having a spare engine just in case.

New pump is £50~£90 according to Alfa Shop (just asked for a rough estimate but their power is off at the moment so they couldn't give me a more accurate estimate).

All the best

Keith

Gary UK · Posted: Mon Sep 08, 2003 3:33 pm Post subject:

Sounds like it has run out of oil in the past then.

Admin · Posted: Mon Sep 08, 2003 4:29 pm Post subject:

Hi

Possibly.

Anyway I am now about £75 worse off. Ordered an oil preasure tester and also a set of noid lights (been meaning to get some for a while). Probably not the best quality going but they should do what I need them to do. Soon should be able to check the oil preasure reading.

All the best

Keith

Matt Stolton · Posted: Tue Sep 09, 2003 8:49 am Post subject: Gauges, Gauges, Gauges.....

The first thing I did to my P4 project was fit oil temp and pressure gauges (and a voltage, but not relevant).

This is going to be very handy. If there is a problem with oil, and, lets face it, none of us even check before every journey, then the gauges warn you before you do expensive damage. Got to be cost effective long term. I liked the MK1 and sud gauges, and feel it was a shame they were cut from mkII + III.

I do like knowing exactly whats going on in an engine, and I much prefer older car's plethoras of lights and gauges. There is something very reassuring about them seeing them all correctly pointing or glowing! Its a bit of a shame that the GTV or GTA didn't get them in the centre console. Would have been a nice touch.

Wiring them is easy (I used electric senders) and I made a plate to fit into the cubby hole by the gearstick, under the heater controls. It just takes 3 x 52mm dials, with a bit of 'Dremmeling'

Best of luck with your engine. Could be a good excuse for an outrageous rebuild......
_________________
Regards

Matt

Ex Alfa 33 'GTA' (P4 with Knobs On)
Now cruising in a 166 3.2 Ti!!

Scott Sander · Posted: Wed Sep 10, 2003 7:53 am Post subject:

Matt,

Where on the engine did you fit the oil temp sensor?
_________________
Scott Sander
'91 Alfa 33 Boxer 16V Monza - Awesome
http://www.sanderfamily.com

Matt Stolton · Posted: Thu Sep 11, 2003 9:00 am Post subject: Oil temp pickup.

The oil temp pickup is fitted into a T adaptor, where the original alfa low oil pressure sensor is fitted, just above the oil filter.

I don't know if this will get enough flow, to accurately give oil temp, as I still haven't got the engine finished yet. However these gauges are not for absolute measurement, they are better used to indicate change from normal. You learn what is normal, and any deviation is a cause to check the engine.

However, all this will proably change, when I get the thermostatic oil cooler send plate fitted. I wil proably move it into the send to the cooler, so I can see the thermostatic plate opening, and then see the temp of the oil going to the cooler.

In an ideal world, you would put lots of sensors everywhere you could, but if you look at too many sensors too often, you will fall off the road. Besides, all that extra weight could slow you down. Cool

_________________
Regards

Matt

Ex Alfa 33 'GTA' (P4 with Knobs On)
Now cruising in a 166 3.2 Ti!!

Scott Sander · Posted: Thu Sep 11, 2003 10:26 am Post subject:

Some time ago I was speaking to an auto instruments guy about oil temp sensors.

He said for it to be effective you need to stick it in the sump, otherwise you could be measuring the temp of the block and not the oil.
_________________
Scott Sander
'91 Alfa 33 Boxer 16V Monza - Awesome
http://www.sanderfamily.com

Admin · Posted: Thu Sep 11, 2003 6:40 pm Post subject:

Hi

Strangely I noticed how warm the engine stayed on the P4. I had warmed the engine up to temp then drained the oil, leaving it draining for ages as I didn't want to be dripped on. Then undid the 1001 bolts that hold the sump on and did the big end shells. Even after that length of time the inside of the engine was still quite warm.

All the best

Keith

Admin · Posted: Sat Sep 13, 2003 3:26 pm Post subject:

Hi

Well, the oil preasure tester arrived. Connected it up and gave it a try. Engine was not fully hot, but about as hot as I wanted it to be before poking around with my hands!

Oil preasure at idle was 3 bar. Take the revs up to the 3000~4000rpm range and the preasure went up to 5 bar.

I cannot find the oil preasure specs on the workshop manual fiche, but those figures sound healthy to me.

All the best

Keith

BILL · Posted: Sat Sep 13, 2003 5:32 pm Post subject:

Admin · Posted: Sat Sep 13, 2003 9:30 pm Post subject:

Hi

This was using an oil preaure gauge for testing, not one to be wired in perminantly. A wired in gauge might be an idea but probably not as accurate.

The engine was fairly warm. Any hotter and I would have burnt my hands trying to connect up the preasure gauge.

All the best

Keith

rjbevan · Posted: Sat Sep 13, 2003 11:10 pm Post subject:

Hi Keith, looking in the Haynes manual the oil pressure relief valve is set to open at 4.5 bar so 5 bar should be OK.

Looking at you shells, it seems strange that the worse score marks are at the centre of the shell, as this is where the oil feed is. So does this suggest oil starvation? Now I know someone who races a Clan and he had 2 engine failures and this was finally traced to the oil pressure relief valve opening and staying open! As you can imagine the shells did'nt last very long (especially at 10,000 rpm). In fact they spun round the crank.

So I presume you do not know the pedigree of the engine, so maybe they got dirt in the oil and this found its way through the system. Maybe the dirt held the pressure releif valve open. Or maybe they used one of those infamous oil filters without an anti-drain back valve and reved the engine too hard when starting.

Anyway, I suppose the engine is back together as you have done a oil pressure test. The suggestion to keep the oil pressure guage in place is a good one as it will tell you of any impending doom. When the oil light comes on it is all too late.

Hope the car is OK.

Richard

Admin · Posted: Sun Sep 14, 2003 12:15 pm Post subject:

Hi

My suspicion is it has just run low. There was also a fair bit of rubbish in the sump pan (including a small piece of plastic about 12mm x 5mm x 3mm Shocked

), so if could be that some rubbish got picked up by the pump and fed into the big end bearings (suspect that is what happened to the number 3 one at least).

I may go and buy an oil preasure gauge to install. The one I used for the test is certainly not suitable for full time installation. The oil light had not come on anyway (the "you've just wrecked your engine light" would be a better description I think).

All the best

Keith