cooling system

3316 Views 27 Replies 7 Participants Last post by John533i, May 9, 2016

roxiedog

Discussion Starter · Jul 12, 2015

1987 Spider Quad has a developed a strange "leak" in the cooling system. The engine would not start and at the same time coolant was spraying out of the vent cap of the overflow tank as the starter cranked. It is just like a little fountain. The rad is full, as is the overflow tank, and neither drain back when the engine cranking stops. Both are still absolutely full of coolant two days after this happened.
it seems that the water pump is pushing coolant from the block into the rad and then to the overflow reservoir, but none is able to pass beyond that. What should I try? Perhaps the bottom hose is plugged, or there is a lot of sediment in the bottom of the rad. Could there be other restrictions further up the line? If anyone has suggestions as to how to proceed, or indeed has had similar difficulties in the past, any advice would be welcome.

1 - 20 of 28 Posts

ghnl

· #2 · Jul 12, 2015

Water pumps don't really develop any pressure (it is the heat that does that).

I'd wonder if you have a failed head gasket. Any evidence of oil in the coolant (not good) or coolant in the oil (really bad)?

roxiedog

Discussion Starter · #3 · Jul 12, 2015

Not really. The coolant is a nice shade of green with no evidence of contamination. The dipstick shows oil at the right level which is also clean and clear. Just to be sure I removed one plug which was dry and clean, so I am cautiously optimistic that the head gasket is OK.

While I said that there was a fountain of coolant coming from the overflow cap, it was actually only going an inch or so in the air each time that the starter turned over. I would guess that would be as expected from the action of the water pump. There was no evidence of the type of pressure you get with coolant at 200 degrees.

Graham

ghnl

· #4 · Jul 12, 2015

I can't really imagine the water pump causing what you describe.

Can you borrow or steal a cooling system pressure tester? It goes on in place of the radiator cap and you can then pressurize the system with an air pump and check for leaks. With the system pressurized you can remove the spark plugs and look/listen for leaks there to rule in/out a head gasket failure. (except it might not totally rule it out because the pressure test is done at say 15-20 psi while the cylinder pressure is 120+ PSI...)

rogerspeed

· #5 · Jul 13, 2015

sounds like the start of head gasket failure, I've been there

roxiedog

Discussion Starter · #6 · Aug 9, 2015

It's been a few weeks since I started this thread and there have been some developments along with some summer activity. After the cooling system fiasco I decided to replace some hoses which were in dire need of replacement and refilled the system. Naturally at that point the overflow reservoir was correctly filled and the overflowing which had happened previously would not happen again since the car would not start.

I then bought a compression gauge and tested the cylinders with the results: 137, 145, 123, 100. Not great, especially since they were all in the low 150's when I bought the car five years ago. I also tried fogging the cylinders for a wet test and all readings increased by 13 psi each. I wonder what that means for the health of the rings?

The car was still not starting and I went through all the ground points and fuses to get the best electrical performance possible. A check of the sparking condition with one of those see-through plugs showed good spark on all cylinders and I also confirmed that the firing order was correct. No start! So next was the fuel pumps which I found were both working correctly and 10.4 volts was on them when the starter motor was engaged. My next move was to have been a check of the fuel pressure, but I had noticed what (I thought) was a change in the sound the engine was making as it turned over on the starter.

This lead me to repeat the compression check. The results were: 0, 0, 28, 30!!! What's with that? I can only assume that the turning over of the engine to check the electrics and fuel has finished toasting the head gasket. Rogerspeed, does this sound halfway familiar? Anyway I also found in another thread on this BB that the overflowing of the cooling system was associated with a breakdown of the head gasket between cylinders. This sounds very much like what is going on with my car and I am now planning to replace the head gasket and rebuild the head. Would it also be sensible to replace pistons and liners while everything is apart? The car has 145,000 km (85,000 miles) on the engine and has not had the head off yet. If I did all that the result would be essentially a rebuilt engine with only the big end bearings not touched as I would hope to do this without removing the block and transmission from the car. Does this sound like a good plan?

See less See more

Alfajay

· #7 · Aug 9, 2015

roxiedog said:
Would it also be sensible to replace pistons and liners while everything is apart? The car has 145,000 km (85,000 miles)

Since adding oil to the cylinders increased the compression readings, your rings are probably worn. So yes, it would be a good idea to disassemble the long block, and at a minimum replace the rings and hone the liners.

Your machinist can assess whether you need to replace the pistons and liners. If the ring grooves in the pistons are still square, and if the liners aren't too worn, they can be re-used.

The machinist should also check the crankshaft and rods, and you should replace the bearings, while you are "in there".

ghnl

· #8 · Aug 9, 2015

roxiedog said:
I then bought a compression gauge and tested the cylinders with the results: 137, 145, 123, 100.

So next was the fuel pumps which I found were both working correctly and 10.4 volts was on them when the starter motor was engaged.

This lead me to repeat the compression check. The results were: 0, 0, 28, 30!!! What's with that?

It is hard to imagine the compression test changing by that much simply from operating the starter motor. And that the previously 'best' cylinders now show no compression.

Before tearing anything apart I'd suggest repeating the compression test. Make sure the battery is fully charged & the throttle propped wide open. And that the compression tester is fully seated into the spark plug hole.

The reading of 10.4V is low. The L-jet computers need ~ 10.5V to wake up and send the make spark/squirt fuel signals.

Alfajay

· #9 · Aug 9, 2015 (Edited)

ghnl said:
It is hard to imagine the compression test changing by that much simply from operating the starter motor.

I have to agree with that. Also, it's tough to get a reading of "0" unless the connecting rod is broken. Re-checking the compression seems like a good idea.

But, even if test #3 matches test #1, there does seem to be a problem with the head gasket. And the 13 psi increase discussed in post #6 (after adding oil to the cylinders) suggests ring problems.

It is always a good idea to fully diagnose problems before tearing an engine apart, because sometimes the issues aren't apparent once it is apart. But eventually, some engine disassembly seems likely here.

roxiedog

Discussion Starter · #10 · Aug 11, 2015

OK, thank you for the observations. I am going to repeat the compression measurements and the voltage at the fuel pump tomorrow.

John533i

· #11 · Aug 12, 2015

My 2 cents- the last bad readings not withstanding, since compression checks are most accurate when the engine is warmed up, I'll bet that you are still in the 150psi range. Cold is always much lower. Also, did you take out the fuel pump relay while you were doing the compression test? You don't want to be washing down the cylinder walls with fuel and contaminating the oil in the sump with fuel.

Good luck. This sounds like a good X-Files Alfa episode...

spiderserie4

· #12 · Aug 12, 2015

roxiedog said:
The car was still not starting....I had noticed what (I thought) was a change in the sound the engine was making as it turned over on the starter.....This lead me to repeat the compression check. The results were: 0, 0, 28, 30!!!

as John 533i just mentioned, sounds to me like "fuel wash".....I bet your various tests have not only flooded, but actually 'washed' the cylinder bores.......when trying to start, it almost sounds as though you have left the plugs out!...the tone is quite different to what you are used to.

Pull the plugs and squirt oil down the bores........leave it there a while then turn the engine over (plugs still out, fuel cut off) to coat the cylinders again.
Then try to start.
If it starts, then on a hot engine do another compression test (but fuel supply cut this time)

rogerspeed

· #13 · Aug 12, 2015 (Edited)

why waste time? you don't need another compression test. Either pressurize the cooling system or proceed to removing the head. With digital fi your problem is not "ring wash". Observed the compression is not right and compression is leaking into cooling system, hence a head gasket problem. Only install a Reinz head gasket. the aftermarket types are not fitting correctly and don't last.

PS - I have a soft spot for Lunenburg, my great-grandfather, Rankin, was a man of the cloth there in the late 1800's

roxiedog

Discussion Starter · #14 · Aug 19, 2015

I took a few days off but it is now so hot outside that an afternoon in the basement garage seemed to be the thing to do. I decided to redo the compression numbers mainly to get further information if possible and the starting point was 10 squirts of engine oil into each plug hole. That was left for two days and then both fuel pumps were disconnected and I turned the engine over a few times. The new compression numbers were: 0, 0, 30, 95. These numbers are with the throttle wide open and all plugs out. So... #4 has improved but the others have remained where they were. I also tried a compression test on #1 with a plug in #2 to see if there was a significant leak between the two. No difference! It would appear that the zero readings on #1 and #2 are independent of each other. And I don't get how a cylinder could have absolutely zero compression without there being a massive meltdown there, but there have been no bad noises coming out of the engine. Shouldn't it be eating up piston rings to get such a result? BTW I also checked that the pistons are indeed going up and down, and yes they are.

So I am thinking that I will blow some compressed air into all the plug holes and see if I can detect where it is ending up (or coming out). Other than that, as Henry VIII would say, it's, "off with her head!".

See less See more

roxiedog

Discussion Starter · #15 · Aug 19, 2015

Compressed air test has been done. With #2 at TDC I blew air at 100 PSI into the bore and it poured out of plug hole #1. Doing the same thing with #3 at TDC air did come from #4 but not nearly as much as in the case of #1-2. Therefore I am guessing that the head gasket is completely gone between #1 and #2, and is compromised to a lesser extent between #3 and #4. Time to start the disassembly.

roxiedog

Discussion Starter · #16 · Aug 29, 2015

Now I am really in need of some help!!. I have been working my way to removing the cylinder head and had got as far as the dissecting of the timing chain. Following the instructions on this BB I turned the engine using the fanbelt assembly and waited for the connecting link to turn up. As I did this I noticed something rather odd: The exhaust camshaft was turning, but the inlet camshaft was not. I think I have found the reason that the car was not running. What do I do now? Is it possible that the timing locknut on the front of the inlet shaft has come loose and only needs to be retightened, or is the shaft actually broken? Is there an efficient way to find out what is going on here? HELP!!

ghnl

· #17 · Aug 29, 2015

Wow! That would explain the odd compression test results! I hope there was no valve/piston damage.

I would proceed with removing the timing chain then remove the camshaft (keep the caps in order - they need to go back where they cam from). Then inspect the cam (post some photos please).

roxiedog

Discussion Starter · #18 · Aug 29, 2015

Thanks Eric. I have pretty much given up for today but I did try moving the very large nut (55 mm?) on the very front of the inlet camshaft and it does turn with just finger pressure. In fact I was able to back it from the shaft until it touched the head casing. I then screwed it back through probably 10 turns until it tightened up against whatever that casting is on the front of the camshaft. it would appear that the locknut which sets the timing had spontaneously unscrewed itself. Is that even possible? Tomorrow I will remove the shaft to make sure that there is no damage, but it looks OK so far. I wonder how the pistons and valves are feeling?

ghnl

· #19 · Aug 29, 2015

roxiedog said:
I did try moving the very large nut (55 mm?) on the very front of the inlet camshaft and it does turn with just finger pressure. ?

Check your Private Messages.

roxiedog

Discussion Starter · #20 · Sep 1, 2015

4

It is now Tuesday and the engine is nicely apart. Both camshafts appear to be in good shape and everything came apart easily. Here are a couple of pictures of the front of the inlet cam: The first one shows the locknut turned out until it hit the casting while the second is after I have turned the nut to tighten it to the VVT unit on the front of the camshaft. http://www.alfabb.com/bb/forums/attachment.php?attachmentid=855145[/IMhttp://www.alfabb.com/bb/forums/attachment.php?attachmentid=855153G] There is an obvious difference if you look closely. Also I found that just hand tightening of this nut was enough to get the inlet cam moving. This really makes me wonder about how that nut would have worked its way loose over time.
The good news is that I could not find any damage to the cams, valves or pistons and the head is now at a local machine shop waiting for valve guides to arrive. Here are two more pictures, one of the cylinder bores and the other of the jury rig I used to pull the head off the studs. I cannot imagine doing this by hand considering the weight of the head and the way it binds on the studs.[url]http://www.alfabb.com/bb/forums/attachment.php?attachmentid=855169http://www.alfabb.com/bb/forums/attachment.php?attachmentid=855177[/url]
Should anything be done with the carbon on the top of the pistons or is it just left alone?

See less See more

1 - 20 of 28 Posts

This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.