UPDATE on engine swap 1.9TD onto a mk1

DieselAlltheWay · Post by **DieselAlltheWay** » Fri Nov 06, 2009 1:19 am

Oops, I was supposed to add this message to a thread I started earlier but somehow it posted as a new thread. Original thread here (please move if possible)
viewtopic.php?t=9523&highlight=

K, here's a much delayed update. It took a while but finally brought the Rabbit home last week. Still a problem I want your smart folks to help me with. But first the update: the 1.9L engine from the donor 93 Golf went in nicely. Thankfully the guy I had doing it is an experienced VW enthusiast and although facing a few challenges there was nothing serious. So thanks to all here for giving me the "green light" to proceed. The car truly is special and I'm very excited about making it my main mode of transportation (well, that and the sports bike).

The problem: I seem to have too much coolant pressure. Is this plausible with the new 1.9TD engine? Here's why I suspect I may have too much pressure in the system which is more than the car seems able to handle.

First incident: very first real drive and the coolant hose that connects to the engine (and goes into the firewall) blows up. Lost all coolant, had to crawl home (with a 6 week old baby in the car!). Car is 25 years old, so I blamed it on age. But now i'm not so sure.

Second incident is that coolant was escaping from the top of the reservoir, where the 2 prong wires connect. It was losing a considerable amount, enough to get the entire engine wet. So I replaced that with the one from the 88 Jetta that I knew was good. Well, shortly after the same problem is happening again.

Am I correct to assume that the amount of pressure generated by this bigger engine to be more than the Rabbit can handle? I was thinking of replacing the reservoir with one that doesn't have the wire connector on the top, since this seems prone to failure in my case. But if I do this, am I only masking a potential problem?

Looking for ideas on this.

rabbit_man · Post by **rabbit_man** » Fri Nov 06, 2009 2:45 am

No I don't think your engine should have more coolant pressure than the 1.6D.

How soon after starting it does it start leaking/bursting hoses etc?

DieselAlltheWay · Post by **DieselAlltheWay** » Fri Nov 06, 2009 2:55 am

It seems to take plainly after I hit the fast roads around here, at speeds around 80 to 100 km/h for a few minutes. It seems the harder I drive and the hotter the engine gets that more coolant is pushed out.

This morning I let the car idle for a good 15 min. No sign of problems. After I return home from an outing I noticed that there was a hiss coming from the top of the reservoir, where the plug connects, along with a few bubbles of coolant. I find it odd that this is happening since I had just put a good reservoir there that had no signs of weakness at the plug area.

As for the hose bursting, I think it may just have been coincidence? Car sat for over 2 years till I got it running again last week. May be a case of old age at that particular rubber hose. But having the reservoir fail like this is suspicious. If in fact there is no additional pressure added to the system than will I be able to replace my reservoir with one without the plug?

Also: for some reason the coolant light (red light) is always on. It comes on shortly after the car is turned on and always stays on. This is the light that typically indicate low coolant level. Even with the coolant at the max line, it still stays on.

Kanzan · Post by **Kanzan** » Fri Nov 06, 2009 6:08 pm

Don't know if this has anything to do with your coolant loss, but here is how I fixed mine. Kanzan

viewtopic.php?t=9701

VW cat · Post by **VW cat** » Fri Nov 06, 2009 7:41 pm

Just some thoughts, there is a test for combustion gases in coolant, Snap-On sells it. Any air bubbles coming into your overflow tank should be suspect, if your coolant system is full with no trapped air. The rad cap controls the cooling system pressure, to increase the boiling point of the coolant. A simple test for a plugged rad is to pour water in the top with a funnel and a pail, it should come out the bottom just as fast. Any coolant level sensor is a great thing if operational and should be mandatory on every car out there. Running a VW diesel without coolant covering the cylinder head is a bad thing, not to mention what it may do to the piston rings. Phil

82vdub · Post by **82vdub** » Fri Nov 06, 2009 8:05 pm

VW cat may be right on. Check for combustion gasses in the coolant. To do this easily, let the car sit all day or over night. Start the car up, and if after 30-60 seconds there's steam or bubbles showing up in the overflow jug, you've got combustion gasses in the coolant. If you've got an oil sludge in the jug, same thing. To ultimately test for a bad head gasket, do a compression test.

You may also want to check to make sure that the water pump is circulating coolant, and that the tstat is operating.

DieselAlltheWay · Post by **DieselAlltheWay** » Fri Nov 06, 2009 8:27 pm

Looks like my choice of words may have pointed to a wrong direction. To clarify I don't have bubbles IN the coolant. What I meant is, coolant was escaping and collecting atop the reservoir, around where the plug connects. With the air pressure escaping from the system it would push into the resting coolant and thus cause it to 'bubble'. So this was a matter of escaping air pushing into the collecting coolant, not bubbles in the cooling system (thank goodness)

Just got home and found yet another interesting discovery: had a partially wet engine again, from escaping coolant from the reservoir. But this time it wasn't escaping from the plug area but instead from the cap. Looks like it's time for a new cap. But I'm almost sure that replacing the cap will mean the coolant will continue to escape from the plug area.

Would my initial idea work? To replace the reservoir with one without a plug?

Post by **Fatmobile** » Fri Nov 06, 2009 11:00 pm

Can you put a pressure gauge on your cooling system?
It would be nice to know if this is happening because of too much pressure or a leaky o-ring.
I think both the cap and coolant level sender are sealed by o-rings,..
oh wait, that's probably the later A2s and on with the o-ring sealing the coolant resevoir.

DieselAlltheWay · Post by **DieselAlltheWay** » Fri Nov 06, 2009 11:06 pm

Fatmobile, the reservoirs in both the 84 Rabbit and 88 Jetta (both TD) are the exact same, both with the black cap and beside it, the plug deal. You're saying that there's an o'ring there that could be worn? That's good to know, hope i can locate said o'ring at my local VW parts store. Failing this do you think it's safe to replace this reservoir with one without the plug? I rather ask dumb questions than to mess things up and really feel dumb afterwards.

Post by **Fatmobile** » Fri Nov 06, 2009 11:22 pm

Keep the resevoir with the level sender.
You are lucky to have one.
If you unscrew the level sender I'm pretty sure you will find an o-ring.

So if the engine is cold and you start it, run it for 30 seconds,...
does pressure build up in the resevoir?

DieselAlltheWay · Post by **DieselAlltheWay** » Sun Nov 08, 2009 2:41 am

Yes, I do have a build of pressure in the reservoir after letting the car run in the morning for 30 seconds. Is this a good thing?
I will be replacing the o'ring for the sensor shortly (even if it means I may have to order one from somewhere in case it isn't a common o'ring), along with a new cap as there is also some steam coming from the cap. Hopefully this will tie up the loose ends in the system. I now feel comfortable knowing that the 1.9L engine doesn't produce more pressure, thanks to responses from the users here. Guess I can mark that hose blowing up to coincidence and old age.

rabbit_man · Post by **rabbit_man** » Sun Nov 08, 2009 3:21 am

DieselAlltheWay wrote:Yes, I do have a build of pressure in the reservoir after letting the car run in the morning for 30 seconds. Is this a good thing?
I will be replacing the o'ring for the sensor shortly (even if it means I may have to order one from somewhere in case it isn't a common o'ring), along with a new cap as there is also some steam coming from the cap. Hopefully this will tie up the loose ends in the system. I now feel comfortable knowing that the 1.9L engine doesn't produce more pressure, thanks to responses from the users here. Guess I can mark that hose blowing up to coincidence and old age.

30 seconds of running from dead cold should NOT produce any pressure.

Quantum-man · Post by **Quantum-man** » Sun Nov 08, 2009 10:10 am

You either have a severely clogged rad, or a non pumping waterpump, or some form of headgasket failure, or majorly over advanced timing
pressurising after 30 secs is very likely partial gasket failure

Vincent Waldon · Post by **Vincent Waldon** » Sun Nov 08, 2009 10:21 am

pressure in a cold cooling system with only 30 seconds of running points a very big finger at a blown head gasket...compression test might make good sense as a next step. All VW coolant systems run at the same 10-15 psi so being an engine swap is not the issue.

Post by **Fatmobile** » Sun Nov 08, 2009 12:57 pm

So a 25psi pressure gauge would work about right to see if pressure is getting too high,..
if the cap is venting at the right pressure over pressure could be caused by a blown head gasket.
Are you sure the stream flowing into the resevoir (through the small line coming from the radiator) isn't spurting? It's a steady stream?